Oracle SQL Plsql

CHAPTER I

Contents

Chapter 1Introduction to RDBMS and ORACLE

7Approaches to Database Management

7Database Management An Evolutionary phenomenon

8Introduction to DBMS

8Concept of DBMS

9Database Models

11Characteristics of Relational Database Management System

11The 12 rules for an RDBMS ( Codds Rule )

11Information Representation

13Application Development Cycle

14Database Designing

15ER Diagram

16Degree of relationship

17Normalization

17Need for normalization

18Steps in normalization

18Invoice Management System

20Invoice Table

20Customer Table

21Oracle as an Object Oriented DBMS

22Features of Oracle

Chapter 2Introduction to SQL *Plus

25Introduction to SQL

25Oracle Data Types

29Starting SQL* Plus editor

31Operators and Expressions

34Querying DataBase Tables

39RollUp Operation Getting sub totals

39Cube Operation Getting cross tabs

Chapter 3Querying Multiple tables42Multiple Table Queries

42EQUI Join

42CARTESIAN Join

43OUTER Join

44SELF Join

45Using Set Operators

46Sub Queries

46Single-Row Sub Queries

47Multiple-Row Sub Queries

47Correlated Subqueries

48Using special operators in subquery

Chapter 4Functions51Functions

51Single Row Function

54Group Functions

Chapter 5Data Definition and Manipulation Language

57Data Definition Language

57Creating Tables

58Working with Constraints

61Creating a table with data from another table

62Maintaining Database Objects

62Alter Table

64The ENABLED/DISABLED Clause

64Dropping / Renaming Tables

65Truncating table

66Insert values into a table

66Inserting result of a query into a table

66Inserting through parameter substitution

67Updating columns of a table

67Deleting rows from a table

68Introduction to Views

68Creating a view

68Manipulating Data through Views

69Creating a join view

69Key-preserved table

70Rules for DML statements on Join View

71Dropping a view

71Working with Sequences

Chapter 6Data Control Language75DataBase Security and Privileges

75Grant Command

76Revoke Command

76Application Privilege Management

76Oracle provides three standard ROLEs:

76Commit and RollBack

77Implicit COMMIT

77Auto ROLLBACK

77Savepoint

Chapter 7Introduction to PL/SQL80Introduction to PL/SQL

80Advantages of PL/SQL

80PL/SQL Architecture

81PL/SQL Block Structure

81Named and Anonymous block

82Conditional and Iterative Control

82IF THEN

83IF THENELSE

83IF THENELSIF

84LOOPEND LOOP

85WHILELOOP

85FORLOOP

86SQL within PL/SQL

86Writing a PL/SQL code

87Composite Data Types

87PL/SQL Records

87Record Assignment

88PL/SQL TABLES

Chapter 8PL/SQL - II92Cursor Management in PL/SQL

92Implicit Cursor

92Explicit Cursor

92Using Cursor

94Explicit cursor attributes

94FOR UPDATE clause within CURSOR

95WHERE CURRENT OF clause

95CURSOR with parameter

96CURSOR FOR LOOP

96CURSOR FOR LOOP Using a Query

97Exception, Errors, and PL/SQL

97Exception handling in PL/SQL

100Exception Propagation

Chapter 9Advanced Pl/SQL105Sub-Programs in PL/SQL

105Advantages of Sub-Programs

105Procedure

106Calling a Procedure

106Actual Vs. Formal parameter

106Argument Modes

108Functions

109Stored Package

110Advantages of package

110Creating a package body:

111Dropping Procedures, Function and Package

112DataBase Trigger

Chapter 10PL/SQL File Input - Output118PL/SQL File Input-Output

118Installation of UTL_FILE package

118Functions and Procedures of UTL_FILE package

Chapter 11Implementing Object Technology123What is Object Technology?

123What is an object?

123Existence of an Object

124Retrieving attribute from an object table

125REF and DEREF operator

128Object with Methods

129Calling a Method

Chapter 12Using Lobs132Large Objects (LOB)

132Creating table with LOBs

132Inserting values on the table

133Updating LOB values

133Data Manipulation in LOBs

134Working with DBMS_LOB package

Chapter 13Collections in Oracle 139Collections

139Nested Tables

139Creating table using Nested Table

140DML operations on Nested Table

140Nested Table in PL/SQL

141VARRAYs

141Creating VARRAYs

142DML operations with VARRAYs

142VARRAYs in PL/SQL

143Similarities and differences between Nested Table and VARRAYs

Appendix A

SQL Reserved Word

Page No : 144

Appendix B

Table Structure

Page No : 145

Appendix C

Hands On Session

Page No : 146

Project

Page No : 149(Snapshots Approaches to Database Management

Database Management An Evolutionary phenomenon

Introduction to DBMS

Concept of DBMS

Database Models

Characteristics of Relational Database Management System

The 12 rules for an RDBMS ( Codd's Rule )

Information Representation

Application Development Cycle

Database Designing

ER Diagram

Degree of relationship

Normalization

Need for normalization

Steps in normalization

Invoice Management System

Oracle as an Object Oriented DBMS

Features of Oracle

(ObjectivesAfter studying this chapter, the student should be able to :

Understand the features of an Object Oriented Database Management System

( OODBMS )

Design Database

Draw E-R Diagrams

Normalize Data Structure

Understand Oracle as an Object Oriented Database Management System ( OODBMS )

Approaches to Database Management

Manual methods of Data Management

Management of Data and Information

Convenient and efficient retrieval

Updating operations

Limitation of Manual Data Management

Physical volume of Data

Human processing of Data

Technological advancement in Data Management

Using computers to speed up processing of Data

Advancement of processing power

Using time-sharing for multiple users

High-speed storage device

Centralize to distributed Database

Centralize to distributed processing (Client-Server)

Database Management an Evolutionary phenomenon

The evolution of database management was accompanied and promoted by:

Advances in computing: Hardware, Operating Syatem and Networking

Drawbacks of the prevalent approach to data management

Data redundancy

Risk to data integrity

Data isolation

Difficult access to data

Unsatisfactory security measures

Poor support of parallel access of data

Data redundancy

Since the files and application programs are written over a long period of time, data in the files is likely to get repeated. This may also lead to inconsistency that is; the various copies of the same data may contain different information. Data redundancy could also occur due to duplication of data at different locations the need for the same data at physically different locations.

Risk to data integrity

The data value stored must satisfy certain integrity constraints. These constraints can be enforced in the system, by adding appropriate code in the application programs. The problem is compounded when constraints involves several data items for different files.

Data Isolation

Since data is scattered in various files, and files may be in different formats, it is difficult to write new application programs to retrieve the appropriate data.

Difficult access to data

Whenever there is a new request, that was not anticipated earlier, there are two possible solutions. Either extract the records manually by mentioning the indexes, access methods, or have the system programmer write the necessary application again with minor changes. This leads to the repeated task of programmer for daily requirements.

Unsatisfactory security measuresEvery user of the system should be allowed to view only that part of the data that is relevant to his department. Since application programs are added to the system in an ad-hoc manner, it is difficult to enforce such integrity constraints.

Concurrent accessMany systems allow multiple users to update the data simultaneously to improve the overall performance of the system and obtain a faster response. But in such an environment interaction of concurrent updates may result in inconsistent data. Since the application programs, which have not been previously coordinated, are used access data, supervision is very difficult to provide.

Database management addressed all this problems, though at the price of increased overheads and costs. However, with the advancement of technology and the all-round development made in hardware, software, networking and OS, the drawbacks of data management have been eliminated to a great extent.

Introduction to DBMS

A programmers productivity tool

Good User Interface

Powerful Database Structure

Advancement of Data Manipulations

Use of 4 GL Tools

A discipline towards data independence

Logical Data Independence

Physical Data Independence

Data View

External View

Conceptual View

Internal View

Concept of DBMSA Database is a collection of interrelated data from which some information can be extracted. A database is designed and built for a specific purpose, keeping in mind the needs of the applications that are going to use it and the end users of those applications. It is managed by a software package known as a Database Management System ( DBMS ).

A DBMS is a general-purpose software system that enables users to define and manipulate databases. It provides an environment, wherein data can be stored and retrieved from database easily and most efficiently. The DBMS is the software used to create and maintain the database.

Database Models

Hierarchical

Network

Relational

Hierarchical Model

This model was introduced in the Information Management System ( IMS ) developed by IBM in 1968. This model is like a hierarchical tree structure, used to construct a hierarchy of records in the form of nodes and branches. The data elements present in the structure have a Parent-Child relationship. A parent unit may have many child units, but a child is restricted to have only one parent. This leads to the repetition of same child record for different parents.

The drawbacks of this model are:

1. The hierarchical structure is not flexible enough to represent all the relationship proportions which occur in the real world.

2. It can not demonstrate the over all data model for the enterprise because of the non-availability of actual data at the time of designing the data model.

3. It can not represent the Many-to-Many relationship.

4. The hierarchical model is used only when the concerned data has a clearly hierarchical character with a single root, for example DOS directory structure.

Network ModelIt is improvement on the hierarchical model. Here multiple parent-child relationships are used. Rapid and easy access to data is possible in this model due to multiple access paths to the data elements.

Transaction is maintained using pointers and tracing the pointers is the drawback of this design.

Relational Model Data is organized in terms of rows and columns in a table known as relations.

The position of a row in a table is of no importance.

The intersection of a row and column must give a single value and not a set of values.

All values appearing in the columns are derived from the underlying schema.

Row must be unique.

Column name must be unique.

All column values are atomic.

In relational database, there are no hard-coded relationships defined between tables. A relationship can be specified at any time using any column names.

The publication of the paper A relational model of Data for large shared database by E.F. Codd in June, 1970 in the Communication of ACM, set a trend for vigorous and extensive investigation into a theoretical frame work to support further work in the area of data modeling. The end result is the Relational Database Management Systems.

SupplierScodeSnameSstatusSCity

S01Agarwal15Delhi

S02Patni20Pune

S03Chandra25Mumbai

S04Keshav15Patna

Parts

PcodePnameWeightPcity

P01Screw8Delhi

P02Nut16Pune

P03Bolt20Mumbai

P04Nut16Patna

Shipment

ScodePcodeQty

S01P01150

S01P02200

S02P03250

S02P04100

S03P01300

Consider the tables shown in the sample database. In table Shipment, each supplier status has a unique supplier code which uniquely identifies the entire row of the table and exactly one name, and city. Likewise each part has a unique Pcode and exactly one name, size and city and at any given time on more than one shipment exists for a given supplier/part combination.

The term Relation is used to describe these tables, which is more precise way of defining than the traditional data processing term File or Table. Rows of such table are referred to as Tuples, again a more precise definition than rows or records and columns are referred to as Attribute. In relational data structure is that association between tuples are represented solely by data values in columns.

Characteristics of Relational Database Management System

Relational database have the following three major characteristics that constitute a well defined RDBMS:

Structures

These are objects that store or access data from the database. Tables, views and indexes are examples of structures.

Operations

These are the actions used to defined the structures or manipulate data between the structures. SELECT or CREATE statements are examples of operations.

Integrity rules

These govern the kinds of actions allowed on data and the database structure. Integrity rules protect the data and the structure of the database. The primary keys and foreign keys are the example of integrity rules.

The 12 rules for an RDBMS ( Codds Rule )


Guaranteed Access

Systematic Treatment of null values

Database Description rule

Comprehensive Data Sub-language

View Updating

High Level Insert, Update and Delete



The Distribution rule

Non-subversion

Integrity rule

E.F. Codd formulated 12 rules for RDBMS in 1970. In addition to the 12 rules, there exists a rule, called rule ZERO, which states:

A relational system must be able to manage databases entirely through its relational capabilities. Any DBMS that advices users to the some non-relational methods to achieve acceptable performance should be interpreted as an apology by the vendor.


In the relational model all the information is explicitly and logically represented by the data values in the tables. This means that even such information as table, view, column names etc. should be contained somewhere as a table form. This makes it necessary for the provision of an active data dictionary that, itself, is relational in nature.

Guaranteed Access

This rule refers to the fact that the table can be taken as a storage structure and at the intersection of each column and row there will necessarily be only one value of data (or null). Every value of data must be logically addressable by using a combination of table name, primary key value and column name.

Systematic Treatment of null valuesIn database management system null values are supported for the representation of missing and in-applicable application. This support for null values must be consistent throughout the DBMS, an independent of data types ( for example, a null value in Char field must mean the same as in an Integer field ).

Database Description rule

A description of the database is stored and maintained the form of tables as is done while defining the data. This allows the uses with appropriate authority to query such information in same ways and using the same languages as they would any data in the database. This implies that a data dictionary should be present within the RDBMS that is constructed of tables and / or views that can be examined using the SQL.

Comprehensive Data Sub-languageThe RDBMS must be completely manageable through its own extension of SQL, although some systems still support SQL like language (e.g. INGRESS support QUEL). The SQL should support data definition, views, data manipulation, integrity constraints, authorization, and transaction boundary.

View Updating

It is a myth that all views that can be updated in theory, can also be updated by the system itself. Though it is possible to create views with all sort of aggregate and virtual columns, it is obviously not possible to update through some of them.

High Level Insert, Update and Delete

An RDBMS must do more than just be able to retrieve relational data sets. It has to be capable of inserting, updating and deleting data as a relational set. A database can not be called relational, if it uses a single record at time procedural technique when it comes to manipulating the data.


User access to database, via monitors or application programs, must remain logically consistent even when changes to the storage representation, or access methods to the data are changed.


Application programs must be independent of the changes made to the base tables. This rule allows many types of database design changes to be made dynamically, without the users being aware of them. A single table should be divisible into one or more other tables, provided it preserves all the original data (non-loss), and maintains the primary key in each and every fragment/table.

The Distribution rule

An RDBMS must have distribution independence. This use one of the most attractive aspects of the RDBMS. Database systems built on the relational framework are well suited to todays client-server database design.

Non-subversion

If an RDBMS supports a lower level language that permits for examples, row-at-a-time processing, then this language must not be able to bypass any integrity rules or constraints of the relational language. Thus, an RDBMS must be governed by relational rules as its primary laws.

Integrity rule

Integrity constraints specific to a particular relational database must be definable in the relational data sub-languages and storable in the catalogue, not in the application programs.

An RDBMS product has to satisfy at least six of the twelve rules of Codd to be accepted as a full fledged RDBMS.

Application Development Cycle

A well designed database makes the application programming and tuning much easier. Before going into the details of database design and modeling, lets review the stages involved in application development.

AnalysisThis is the first stage of an application development, and it should enable you to answer the following questions:

1. Why is the application being developed?

2. Who is going to use it?

3. How will the application benefit the users?

4. What business rules and needs should be addressed?

The complete functionalities of the system should be determined in requirement analysis. Typically, functional-level managers take care of this phase.

DesignThis is the most important phase of application development. After the application requirements are analyzed, the design phase begins. In this phase, the database design is performed using ER diagrams. The logical database design is converted to physical structures.

Development

In the development phase, coding is done based on the design; you use the end product of the design phase of the life cycle as a building block for the development process. The database design and the designed system requirements provide the basis for the development of the application.

TestingThe developed application is tested against its objectives to ensure that it is doing what it is supposed to do. System/Integration testing is done on the entire system. Any errors are corrected, and the application is tested again. Application users do the acceptance testing.

Implementation

Implementation is the final stage in the development cycle. Once the testing is complete, the application is ready to implement. Errors reported after implementation is fixed by going back to the appropriate stage.

Database Designing

Requirement, formulation and analysis

Collection and documentation of requirement

Analysis of requirement

Conceptual design

Data Modeling

1st Level-ER (Entity-Relationship) Modeling

2nd Level-Normalization

Physical Model

Requirement, formulation and analysis

The objective of this phase to answer the following question:

What are user views of the data (Present and Future)?

What data elements are required in these user views?

What are the entities and their primary keys?

What are the operational requirements regarding security, integrity and response time?

Conceptual Design

The major step in conceptual design is to identify the entities and relationships that reflect the organizations data. The objective of this step is to specify the conceptual structure of the data and is often referred to as data modeling. The ER model, with an emphasis on the top-down approach.

Data ModelingData modeling is achieved in two levels; the 1st level builds the conceptual model of the data, using ER modeling. The 2nd level organizes this model better, by removing redundancies, through a process called normalization. The normalized model is then converted into the physical database.

Physical Model

You create a physical model by using the logical model to assist in creating a database and database objects to represents to entities and relationships. In the physical model, each entity becomes a table, and attributes of the entity become columns of the table. The relationship between the entities is part of one or more constraints between the tables. Physical implementation might require you to combine, separate, or create completely new entities in order to best realize the logical model. The unique identifiers of an entity become the primary key of the table. You may create stored procedures, functions and triggers to enforce business rules.

ER Diagram

Entity Relationship modeling is a technique for analysis and logical modeling of the system data requirements. It uses three basic concepts, entities, their attributes and the relationship that exists between the entities. It uses graphical notation for representing these.

Graphical notation for ER diagram

NAMESYMBOLFUNCTION

EntityData object in the system uniquely identifiable by identifier has attributes that describe it.

Attribute

Describes an entity

Relationship

Relates two entities uniquely identified by the identifier

EntityAn entity is an object, place, person, concept, activity about which an enterprise records data. It is an object which can have instances or occurrences. Each instance should be capable of being uniquely identified. Each entity has certain properties or attributes associated with it and operation applicable to it. Entity type and entity instance are two important term related to entities. An entity type is a set of things which shares common properties. An entity type is usually denoted in upper case. An entity instance is a specific individual thing. An entity instance is usually denoted in lower case.

Example of entity type: STUDENT COURSE, COURSEWARE DEVELOPMENT TEAM etc.

Example of entity instance: sudipta, physics etc.

Attributes

Attributes are data element that describes an entity. If the attribute of an entity has more attributes that describe it, then it is not an attribute of that entity, but another entity. Attributes can either be listed next to the entities, or placed in circle and attached to the entity. Identifier is one or more attributes of an entity or relation, whose value uniquely identifies the entities or relationships.

Relationship

This is an association between entities. It is represented by a diamond in the ER diagram. Relationship can also have properties and attributes associated with it.

Degree of relationship

ONE to ONE (1:1)

ONE to MANY(1:N)

MANY to MANY(N:N)

The degree of relationship indicates the link between two entities for a specified occurrence of each. The degree of relationship is also called cardinality.

ONE to ONE

This relationship is one in which each occurrence of one entity is represented by single occurrence in another entity. For example, consider an individual and that individuals social security number: One person can have only one social security number, and a social security number can belong to only one person.

ONE to MANY

This relationship is one in which an occurrence of one entity may be represented by many occurrence in another entity. An example is department and employees: One department has one or more employees, and an employee belongs to only one department.

MANY to MANY

This relationship in which an occurrence from one entity may be represented by one or more occurrence in another entity, and an occurrence from second entity may be represented by one or more occurrence in the first entity. The relationship between Doctor and Patient is an example: A patient can visit many doctors, and a doctor can have many patients.

Note: MANY to MANY relationship should not exists in RDBMS because they can not be properly joined to represent a single row correctly. To solve this, create another entity that has a ONE to MANY relationship with the first entity and a ONE to MANY relationship with the second entity.

When you have established the relationship between entities, it is time to normalize the design.

Normalization

Refinement of the ER Model.

Segregation of data over many entities or tables.

Normalized model converted to physical database tables.

Normalization is the process of refining the data model built by the ER Diagram. The normalization technique, logically groups the data over a number of tables, with minimum redundancy of data.

The goal of the relational data base design is to generate a set of relation scheme that allows us to information with minimum redundancy of data and allow us to retrieve information easily and efficiently.

The first step towards normalization is to convert the ER model into tables or relations. The next step is to examine the tables for redundancy and if necessary, change them to non-redundant forms. This non-redundant model is then converted to a database definition.

Need for normalization

Improves database design.

Ensures minimum redundancy of data.

Reduces need to re-organize data when design is modified/enhanced.

Removes anomalies for database activities.

Un-Normalized Data Structure

Supplier CodeSupplier NameSupplier StatusCity SupplierPart CodePart NameWeightQtyCity Sold

S01Agarwal15Delhi101Screw8500Kolkata

S02Patni20Pune102Nut16250Meerut

S03Chandra25Mumbai103Bolt20250Ranchi

S04Keshav15Patna102Nut16300Silvasa

S05Bhushan25Kolkata104Bolt2050Pune

S06Menon15Guahati102Nut16200Patna

Above table structure presents several difficulties in operations like:

Insertion in fields If new field is introduced into the system, it can not be added to the database, until becomes related to another existing field, e.g. if supplier name is introduced its details can not be entered in the table unless a part name is represent for that supplier.

Updation of fields If the supplier code of a supplier is to be modified, it has to be changed throughout the table, in all occurrence of the supplier record. Missing out even a single correction, would result in incorrect data.

Deletion of fields If information related to a specific column is to be deleted, the entire row has to be deleted, which results in loss of required information. For example, if the row of the supplier Saleh is deleted, the information about the part name is lost. Deletion of supplier detail also deletes other details.

Steps in normalization

First Normal Form (1NF)

Identify a repeating fields

Remove repeating groups to a separate table

Identify the keys for the table

Key the parent table is brought as part of the concatenated key of the second table

Second Normal Form (2NF)

Check if all fields is dependent on the whole key

Remove fields that depend on part of the key

Group partially-dependent fields as a separate table

Name the tables

Identify key(s) to the table(s)

Third Normal Form(3NF)

Remove fields that

Depend on other non-key attribute

Can be calculated or derived from logic

Group independent fields as separate tables, identify the key and name of the table

Invoice Management System

An invoice management system accepts items and customer details from the user and prepares invoices. The item details include item description, quantity sold, rate and discount (if applicable). For each order the customer is given an invoice. Each invoice can have details of more than one item.

The raw table containing invoices details: Un-normalized

InvnoInvdateOrdnoChlnoCustnoCustnmItnoItdescQtyRateDisInval

11212/08/9711C1AshokeI1Pepsi28Nil16

11212/08/9721C1AshokeI2Butter122Nil22

11316/08/9711C4VipulI3Bread112Nil12

11416/08/9711C1AshokeI8Biscuit222Nil44

11416/08/9721C1AshokeI2Butter422Nil88

First Normal Form

The attributes invno, invdate, ordno, chlno, custno and inv_val are repeating groups in the invoice table. These attributes can be are split into a separate table called invoice table which contains the invno, invdate, ordno, chlno, custno and inval.

The identifier of this table is invno. The other table is called invoice items which contains invno, into, itdesc, qty, rate and dis. The identifier of this table is invno and into which identifies a single row.

Invoice Table

InvnoInvdateOrdnoChlnoCustnoCustnmInval

11212/08/9711C1Ashoke16

11212/08/9721C1Ashoke22

11316/08/9711C4Vipul12

11416/08/9711C1Ashoke44

11416/08/9721C1Ashoke88

Invoice Items

InvnoItnoItdescQtyRateDis

112I1Pepsi28Nil

112I2Butter122Nil

113I3Bread112Nil

114I8Biscuit222Nil

114I2Butter422Nil

Second Normal FormThe invoice item table is further split, by removing itdesc and rate which are not dependent on the full concatenated key (invno+itno). The new table is named as ITEMS table which contains itdesc, rate and itno as its primary key. The identifier of this table is itno, which identifies a single row.

The remaining attributes in the invoice item table consists only of, invno, itno, qty and dis. The identifier here is invno+itno which identifies a single row. Here each elements is dependant on full concatenated key.

Invoice TableInvnoInvdateOrdnoChlnoCustnoCustnmInval

11212/08/9711C1Ashoke16

11212/08/9721C1Ashoke22

11316/08/9711C4Vipul12

11416/08/9711C1Ashoke44

11416/08/9721C1Ashoke88

Invoice Items

InvnoItnoQtyDis

112I12Nil

112I21Nil

113I31Nil

114I82Nil

114I24Nil

Item Table

ItnoItdescRate

I1Pepsi8

I2Butter22

I3Bread12

I8Biscuit22

I2Butter22

Third Normal FormThe invoice table derived from the un-normalized table is now in the second form can be further normalized. There is still a dependency between non-key attributes: custnm depends upon custno, a non-key attribute. custnm is removed to the CUSTOMER table, with custno as the key. The remaining attributes remain in the INVOICE table with invno as the key.

Invoice TableInvnoInvdateOrdnoChlnoCustnoIn_val

11212/08/9711C116

11212/08/9721C122

11316/08/9711C412

11416/08/9711C144

11416/08/9721C188

Customer TableCustnoCustnm

C1Ashoke

C4Vipul

Invoice Items

InvnoItnoQtyDis

112I12Nil

112I21Nil

113I31Nil

114I82Nil

114I24Nil

Item Table

ItnoItdescRate

I1Pepsi8

I2Butter22

I3Bread12

I8Biscuit22

I2Butter22

Oracle as an Object Oriented DBMS

Oracle is an ORDBMS. It lets you define user defined object types in the relational database system. Object types are structures that consists of built-in or user-defined data types. For example, an address can be defined as an object type and can be referenced in tables:

Customer_Table

Cust_nameVarchar2(40)

Cust_addrAddress_Type

Cust_phoneVarchar2(12)

Cust_faxVarchar2(12)

Where Address_type is an object type defined as

Address_Type

StreetStreet_Type

CityVarchar2(30)

StateChar(2)

ZipNumber(5)

Where Street_Type is defined as :

Street_Type

Street_number

Number(6)

Street_name1

Varchar2(40)

Street_name2

Varchar2(40)

Apartment_no

Varchar2(5)

Now that the Address_Type is defined, it can be used in number of tables where addresses need to be stored. This small example shows the reusability of objects.

Features of Oracle

High transaction processing performance All the facilities for transaction and its recovery in case of any failure are supported in Oracle for better performance of transaction processing.

Industry accepted standards All the recent technologies like object oriented technology and distributed data processing are supported in Oracle .

Manageable Security Very strong security provisions are there inside Oracle to guard against malicious users.

Large database support In supporting large database, Oracle is more reliable compared to any other database packages.

Concurrent Processing More than one user can work simultaneously on the same database without any interference.

Client/Server environment It supports client server technology i.e. the server contains the main database and clients ( users ) can access the database to fetch and manage only that data for which they are given the authorization.

Distributed database system Oracle supports distributed environment i.e. applications made on different platforms and in different environments can exchange the data with the common interface language called Interface Definition Language ( IDL ).

Portability Runtime models made inside Oracle environment can run without any changes on other compatible platforms easily.

Compatibility It is compatible with all sorts of front ends although, Oracle has its own front end but still Oracle database can be used with other front ends like Visual Basic, VC++ etc. easily.

(Snapshots

Introduction to SQL

Oracle Data Types

Starting SQL* Plus editor

Operators and Expressions

Querying DataBase Tables

RollUp Operation - Getting sub totals

Cube Operation - Getting cross tabs

(Objectives

After studying this chapter, the student should be able to :

Understand the Structured Query Language ( SQL )

Understand the Datatypes supported by Oracle

Log on to Oracle

Query database tables using SQL statement

Understand how to use Aggregate Functions

Understand Order by and Group by clause

Understand ROLLUP and CUBE operation

Introduction to SQL

The language used to access data within Oracle database

Developed in a prototype RDBMS, System R, by IBM in mid 1970s

Oracle Corporation introduced the first commercially available implementation of SQL

ANSI adopted SQL as a standard language for RDBMS in October 1986

Key features of SQL are:

Non-procedural language

Unified language

Common language for relational database

SQL (Structured Query Language) pronounced as see-quell is made of three sub-languages such as:

Data Definition Language (DDL): Consists of commands Create, Alter, Drop to create or remove objects such as Tables, Views, and Indexes etc.

Data Manipulation Language (DML): Used for query, Insertion, Deletion and Updation of information stored in the database.

Data Control Language (DCL): Used for controlling data and access to the databases. Examples: Commit, Rollback.

SQL *Plus is a software product from Oracle Corporation that allows users to interactively use the SQL commands, produce formatted reports and support written command procedures to access Oracle database.

Through SQL *Plus a user can:

Enter, edit, store, retrieve and run SQL commands

Format, perform calculation, store, print query result in the form of reports

List column definition of any table

Access and copy data between SQL databases

Send messages to and accept responses from an end user

Oracle Data Types

When you create a table to store data in the database, you need to specify a datatype for all columns to define in the table. Oracle has different datatypes to suit your needs. The datatype are broadly classified into Character, Number, Date, LOB and RAW datatypes. Oracle lets you use user-defined datatypes, but they are constructed from the basic datatypes.

Character Datatypes

Character datatypes are used to store alphanumeric data. When you define character data in Oracle , you specify a length for the column, which is the maximum width of the column. In Oracle you can have different type of datatype to store alphanumeric value:

CHAR() The CHAR datatype is a fixed-length character string having a maximum length of size. Data stored in CHAR column is space-padded to fill the maximum length. The size can range from a minimum of 1 to maximum of 2000 characters.

When you create a column using the CHAR datatype, the database will ensure that all data placed in this column has the defined length. If data is shorter than the defined length, it is space-padded on right to the specified length. If the data is longer, an error is raised.

VARCHAR() A VARCHAR datatype in Oracle is synonymous with the VARCHAR2 datatype.

VARCHAR2() The VARCHAR2 datatype is a variable-length alphanumeric string having a maximum length of size bytes. VARCHAR2 variables only require the amount of space needed to store the data. VARCHAR2 database columns can store up to 4000 bytes and VARCHAR2 variables up to 32676 bytes. An empty VARCHAR2(2000) column takes up as much room in the database as an empty VARCHAR2(2) column.

The default size of the CHAR datatype is 1. In VARCHAR2, you must always specify the size.

LONG The LONG datatype is a legacy datatype that will no longer be supported in the future. It has been deprecated in favor of large object datatype. A LONG datatype column is of variable length and can take up to 2GB. There are many restriction on the use of LONG columns and variables. LONG columns can not appear in Where clause, Group By clause, Order By clause or with the Distinct operator in Select statements.

Numeric Datatype

Numeric datatype are used to store negative and positive integers: fixed-point and floating-point numbers with a precision of up to 38 digits. Specifying a number outside this range will raise an error.

Number(,) The number datatype stores numbers with a precision of p digits and a scale of s digits. The precision and the scale value are optional. Specifying the scale and precision does not force all inserted values to be a fixed length. If the number exceeds the precision, however, an Oracle error is returned. If the number exceed the scale, it is rounded to the scale. If the scale is negative, the number is rounded to the left of the decimal. Basically, a negative scale forces s number of zeros just to the left of the decimal.

Precision and scale example

Actual ValueDatatypeStored Value

1234567.89Number1234567.89

1234567.89Number(8)1234568

1234567.89Number(6)Numeric Error

1234567.89Number(9,1)1234567.9

1234567.89Number(9,3)Numeric Error

1234567.89Number(7,2)Numeric Error

1234567.89Number(5,-2)1234600

1234511.89Number(5,-2)1234500

1234567.89Number(5,-4)1230000

1234567.89Number(*,1)1234567.9

Date Datatype

The Date datatype is used to store date and time information. This datatype can be converted to other forms for viewing, and it has number of special functions and properties that makes date manipulation and calculation simple. The Date datatype occupies a storage space of 7 bytes. The following information is contained within each date datatype:

Century Year Month Day Hour Minute Second

The default format for Oracle Date datatype is DD-Mon-YY; this is the format shown whenever a date is selected within SQL *Plus.

LOB DatatypeLarge object datatypes store blocks of unstructured data, such as a binary file, a picture, or an external file. A LOB can store data up to 4GB. The data may be stored in the database or in an external file. LOB data maniputaion is done using the DBMS_LOB package.

Datatype PurposeDescription

BLOBBinary Large ObjectCan store up to 4GB of binary data in the database.

CLOBCharacter Large ObjectCan store up to 4GB of character data in the database. Oracle converts the data into Unicode format and stores it in the database.

BFILEBinary FileStores binary data up to 4GB in operating system files outside of the database. The size of the binary file must conform with operating system limitations on file size. A BFILE column stores a file locator that points to an external file containing the data. BFILE datatypes are read-only; You can not modify them.

Note : There may be more than one LOB datatype column in a table, but there can be only one LONG datatype column.

Other Datatypes

Oracle has RAW datatypes in addition to the character, numeric and date datatypes.

RAW RAW is unstructured, binary data that is not interpreted by the database. RAW columns can be up to 2000 bytes long.

LONGRAW Like the LONG datatype, LONGRAW is a legacy datatype that has been deprecated in favor of the LOB datatypes BLOB or BFILE. LONGRAWs can store up to 2GB of unstructured data. LONGRAW data cannot be indexed, but RAW data can be indexed.

Literals

Literals are values that represent a fixed value. There are three types of literals values:

Text

Integer

Number

Text literals must be enclosed in single quotes; integer and number literals need not be. You can use literals within many of the SQL functions, expressions and conditions.

Text The text literal must be enclosed in single quotation marks. Any character between the quotation marks is considered part of the text value. Oracle treats all text literals as though they were CHAR datatypes. The maximum length of a text literal is 2,000 characters. Single quotation marks can be included in the literal text value by preceeding it with another single quotation mark.

Here are some examples:

The quick brown fox

That mans suit is black

And I quote:This will never do.

Integer Integer literals can be any number of numerals, excluding a decimal separator and up to 38 digits long.

Examples follow:

24

-456

Number Number literals can include scientific notation, as well as digits and the decimal separator.

Here are some example:

24

-345.65

23E10

Starting SQL* Plus editor

Step I : Locate the Oracle short cut in your desktop. If it is not there try to get it from Start>Programs menu.

Step II : Double click or press on the short cut shown above.

Step III : Provide the User Name, Password and Connect String in the dialog shown. The Connect String is nothing but the Database name.

After providing the User Name, Password and Connect String click on the OK button. If all the information you have provided is correct then you will get the following screen.

Tables used in Examples

DEPT-Contains information about the departments in the company

EMP-Contains information about the employees of that company

Structure of DEPT table

Column namesType(Size)DescriptionConstraints

DEPTNONUMBER(2)Department numberPrimary Key

DNAMEVARCHAR2(20)Department nameNOT NULL

LOCVARCHAR2(10)Location of the departmentNOT NULL

Data of DEPT Table :

Structure of EMP table

Column namesType(Size)DescriptionConstraints

EMPNONUMBER(4)Employee numberPrimary Key

ENAMEVARCHAR2(20)Employee nameNOT NULL

JOBVARCHAR2(10)DesignationNOT NULL

MGRNUMBER(4)Respective managers EMPNO

HIREDATEDATEDate of JoiningNOT NULL

SALNUMBER(9,2)Basic SalaryNOT NULL

COMMNUMBER(7,2)Commission

DEPTNONUMBER(2)Department numberNOT NULL, Foreign Key

Data of EMP Table :

Operators and Expressions

An operator is a manipulator that is applied to a data item in order to return a result. Special characters represent different operations in Oracle. Operators may be classified into two types :

Unary Operators : A unary operator has only one operands. +2 and 5 are examples. They have the format < operator operand >

Binary Operators : Binary operators have two operands. 5+4 and 7 x 5 are examples. They have the format < operand1 operator operand2 >

Arithmetic Operators

Arithmetic operators operate on numeric datatypes.

OperatorPurposeExample

+ - Unary operators: Use to represent positive or negative data item. For positive items, the + is optional.-234.45

+Addition: Use to add two data items or expressions.3 + 7

-Subtraction: Use to find the difference between two data items or expressions.7 - 5

*Multiplication: Use to multiply two data items or expressions.5 * 10

/Division: Use to divide a data items or expression with another.8 / 4

Concatenation Operator

This operator is used to concatenate or join two character ( text ) strings. The result of concatenation is another character string. If one of the strings is NULL, the result is also NULL. Concatenating a zero-length string( ) with another string results in a string, not a NULL. Two vertical bars ( || ) are used as the concatenation operator. Here are a few examples:

Oracle || Database results in OracleDatabase Oracle || Database results in Oracle DatabaseComparison Operator

Comparison operators compare two values or expression and give a Boolean result of TRUE, FALSE, or NULL. Comparison operators are mainly used in the WHERE clause of the SQL statement.

OperatorPurposeExample

=Equality test SELECT * FROM emp WHERE ename=SCOTT;

!=

^=Inequality testSELECT * FROM emp WHERE ename!=SCOTT;

2000;

>=Greater than equal toSELECT * FROM emp WHERE sal>=2000;

ALL(SELECT sal FROM emp WHERE deptno=20);

The above will display all employees name whose salary is greater than the highest salary of all employee belonging to department 20.

(Snapshots

Functions

Single Row Function

Arithmetic Functions

Character Functions

Date Functions

General Functions

Group Functions

(Objectives


Understand what are Functions

Type of Functions

Understand the use of various column functions and group functions

Functions

Functions are programs that take zero or more arguments and return a single value. There are two significant classes of function:

Single Row Function

Group Function

Single Row Function

Single Row Function knows how many arguments they will have to process before data is fetched from the tables.

Can be used to manipulate data items

Accept arguments (number of arguments varies from function to function)

Always returns a single value

Act on each row returned

Can be used to modify the data type

Can be nested in other functions

To test all the following functions you can work with the table called dual. This table has only one column in its structure. The column name is dummy and it has only one row with a value x.Arithmetic functions

ABS (x)Absolute Value of x

CEIL (x)Smallest integer greater than or equal to x.

FLOOR (x)Largest integer less than or equal to x.

MOD (x,y)Returns the remainder of x divided by y

POWER (x,y)Returns x raised to the power of y. The 2nd argument must be an integer

SIGN (x)Returns 1 if x is negative, 1 if positive and 0 if it is zero

SQRT (x)Returns the square root value of x. If x is null or negative then null is returned

ROUND (x,[y])Rounds the value x, up to y decimal places. If y is omitted it is rounded to no decimal places. If y is negative number to left the decimal are rounded

TRUNC (x, n)Truncate x to n decimal places to the right of the decimal point.

Character functions

CHR (x)Character for ASCII value x.

ASCII (c)Returns the ASCII value of c

INITCAP (s)String s with the first letter of each word capitalized

LOWER (s)Converts string s to all lower case letters

UPPER (s)Converts string s to all upper case letters.

LPAD (s, x)Pads string s with x spaces to the left.

RPAD (s, x)Pads string s with x spaces to the right.

LTRIM (s)Removes leading spaces from s.

RTRIM (s)Removes trailing spaces from s.

REPLACE (s1, s2, s3)Replace occurrences of s1 with s2 in string s.

TRANSLATE (s1, s2, s3)Returns s1 with all occurrences of each character in s2 replaced by the corresponding character in s3.

SUBSTR (s, x1, x2)Return a portion of string s starting at position x1 and ending with position x2. If x2 is omitted, it's value defaults to the end of s.

INSTR (s1, s2, x)Returns the position of s2 in s1 where the search starts at position x.

LENGTH (s)Length of s

Date Functions

SYSDATEReturns the system date

ADD_MONTHS(d,n)Add or subtract months to or from a date. Returns a date as the result

MONTHS_BETWEEN(d1,d2)Returns number of months between two dates

LAST_DAY(d)Returns the date of the last day of the month specified. The result will be a date

NEXT_DAY(d,day)Returns the date of next specified day of the week after the date d

Conversionfunctions

TO_CHAR (date, format)Converts a date column to a string of characters. format is a set of Date formatting codes where:YYYY is a 4 digit year.MM is a month number.MONTH is the full name of the month.MON is the abbreviated month.DDD is the day of the year.DD is the day of the month.D is the day of the week.DAY is the name of the day.HH is the hour of the day (12 hour clock)HH24 is the hour of the day (24 hour clock)MI is the minutes.SS is the seconds.

TO_CHAR (number, format)Converts a numeric column to a string of characters. format is a set of number formatting codes where:9 indicates a digit position. Blank if position value is 0.0 indicates a digit position. Shows a 0 if the position value is 0.$ displays a leading currency indicator.

, used as a group separator

TO_DATE (s, format)Converts a character column (string s to a date. format is a set of Date formatting codes as above

TO_NUMBER (s, format)Converts a character column (string s to a Number. format is a set of Number formatting codes as above.

OtherfunctionsDECODE (s, search1, result1, search2, result2)Compares s with search1, search2, etc. and returns the corresponding result when there is a match.

NVL (s, expression)If s is NULL, return expression. If s is not null, then return s.

USERReturns the username of the current user.

Group Functions

Group function dont know how many arguments they will have to process until all the data extracted and grouped into categories. To use an aggregate function, a GROUP BY clause must be added to the SELECT statement. Group function do not process a null value and do not return a null value.

AVG (col)Returns the average of a group of rows for col

MAX (col)Returns the maximum of a group of rows for col

MIN (col)Returns the minimum of a group of rows for col

SUM (col)Returns the sum (total) of a group of rows for col

COUNT (columns)Returns the number of instances of a group of rows for (columns)

(Snapshots

Data Definition Language

Creating Tables

Working with Constraints

Creating a table with data from another table

Maintaining Database Objects

Alter Table

The ENABLED/DISABLED Clause

Dropping / Renaming Tables

Truncating table

Insert values into a table

Inserting result of a query into a table

Inserting through parameter substitution

Updating columns of a table

Deleting rows from a table

Introduction to Views

Creating a view

Manipulating Data through Views

Creating a join view

Key-preserved table

Rules for DML statements on Join View

Dropping a view

Working with Sequences

(Objectives


Understand how to create tables

Understand what are constraints

Understand how to alter a table

Understand how to insert values into a table

Understand how to update column(s) of a table

Understand how to delete row(s) from a table

Understand what are views

Understand how to manipulate base table(s) using views

Understand how to work with sequence

Data Definition Language

DDL is a subset of SQL commands used to create, modify or remove Oracle database structure.

Example: Tables, Views. These command have an immediate effect affect on the database, and also record information in the data dictionary.

Creating Tables

Tables are created using the CREATE TABLE command

Tables are owned by the user who creates them

The names of table owned by a given user must be unique

The column names in a table must be unique

Naming convention of a table

The table name must begin with a letter

It may contain letters, numerals and special character

It may be up to 30 characters long

A table name must not be a SQL reserved word

Table name is not case sensitive

Table names are stored in uppercase except those given in double quotes

Syntax:

CREATE TABLE

(

,

..

);

Example:

Create a table ITEM_MAST, which has the following columns:

Column NameTypeSizeDescription

ITNONumber4Item Number

ITNMVarchar220Item Name

CLASSChar1Category of item

QOHNumber5Quantity On Hand

RATENumber8,2Item Unit Price

CREATE TABLE ITEM_MAST

(

ITNO

Number(4),

ITNM

Varchar2(20),

CLASSChar(1),

QOH

Number(5),

RATE

Number(8,2)

);

Working with Constraints

Constraints are used to enforce data integrity. Constraints are rules and as such dont take up space in a database as a table dose. Instead, constraints exist only in the data dictionary and are applied during the execution of SQL and PL/SQL. When constraints are enabled, they are enforced. When constraints are disabled, they are not enforced, but they still exist in the data dictionary. There are five varieties of constraints :

Check

NOT NULL

Unique

Primary key

Foreign key

Default

Check Constraints

Check constraints require a specific Boolean condition on a column or set of columns to be true or at least one of the column values to be NULL. Check constraints are enforce simple business rules about the content of data in your tables. Check constraints cannot protect columns of datatype LOB, object, nested table, VARRAY. If the check protects a single column, it can be created inline with the column in the CREATE TABLE statement. A check constraint can also be created or added as a table constraint. When it protects two or more columns, you must use the table constraint syntax. The constraints name is optional and, if this name is not present, Oracle will generate a unique name that begins with SYS_. You should not rely on system-generated names for constraints.

Example :

CREATE TABLE ITEM_MAST

(

ITNO

Number(4),

ITNM

Varchar2(20),

CLASS Char(1) constraint ch_class check (CLASS IN ( A, B, C ))

QOH

Number(5),

RATE

Number(8,2),

Constraint ch_classrate CHECK (( CLASS = A AND RATE VALUES ;

Example :

INSERT INTO ITEM_MAST

VALUES ( 111,Baby Food, A, 75,125.75);

While inserting data into table, the following points should be remembered:

Character data will be enclosed within quotes

Column values for date type of column are provided within single quotes. Oracle internally converts the character field to date type field

NULL values are given as NULL, without any quotes because null is a true value

If data is not available for all columns, then the column list must be included, following the table name.

Example :

INSERT INTO ITEM_MAST ( itno, itnm, class)

VALUES ( 111,Baby Food, A);

Inserting result of a query into a table

In order to use query with insert, the target table must fulfill the following conditions:

The table must be an existing one

It must have the columns retuned by the query and be of the same data type

Example:

INSERT INTO itmast SELECT itno, itnm, class FROM item_mast;

Inserting through parameter substitution

The parameter substitution provides an easier way to insert data into a table. The & sign is used as the substitution operator.

Example:

INSERT INTO itmast VALUES(&itno, &itnm,&class);

Updating columns of a table

UPADTE command is used to update the column values in a table Values of a single column or a group of columns can be updated

Updation can be carried out for all the rows in a table or selected rows

Syntax:

UPDATE SET =value

[,=value,] [WHERE ];

Example:

UPDATE itmast SET qty=100 WHERE into=111;

Deleting rows from a table

DELETE statement is used to delete rows from a table The entire row is deleted from the table

Specific column value can not be deleted from a table

CASCADE DELETE rule instructs DBMS to automatically set the foreign values to NULL in the child rows, if the parent row is deleted

Syntax:

DELETE FROM [WHERE ];

Example:

DELETE FROM emp;

DELETE emp;

Both the statements are same and will delete all the rows from the emp table.

Introduction to Views

A view is a customized representation of data from one or more tables. The view takes the result of a query and stores it in the database. A view can be considered to be as a stored query or a virtual table. Only the query is stored in the Oracle data dictionary; the actual data is not copied anywhere. So, creating views does not take any storage place, other than the space in the data dictionary. The views can have different column names than the base table. You may create a view to limit the data accessible to the other user.

Creating a view

A view can be created using the following syntax:

CREATE VIEW [] AS ;

Example:

CREATE VIEW empview AS SELECT empno,ename,deptno FROM emp WHERE deptno=20;

Now to select the rows from the view you can use the following statement:

SELECT * FROM empview;

Manipulating Data through Views

The INSERT, UPDATE and DELETE statements can also be used with views Using these commands with views is an indirect way of manipulating tables

WITH CHECK OPTION clause allows integrity constraints and data validation to be enforced on data being inserted or updated

Join view can also be modified

Key-preserved table is used to understand the restriction on modifying join views

The WITH CHECK OPTION clause

This clause specifies that inserts and updates performed through the view are not allowed to create rows which the view can not select. Let us consider the above view:

Suppose we insert the following:

INSERT INTO empview VALUES(1234,PAUL,30);

The row will be inserted without any error. But if we create that view with the following statement the above insert statement will generates an error:

CREATE VIEW empview AS SELECT empno,ename,deptno

FROM emp WHERE deptno=20 WITH CHECK OPTION;

Constraint name can also be assigned to the WITH CHECK OPTION:

CREATE VIEW empview AS SELECT empno,ename,deptno

FROM emp WHERE deptno=20 WITH CHECK OPTION CONSTRAINT mycons;

Creating a join view

CREATE VIEW myview AS SELECT empno, ename, dname

FROM emp, dept WHERE emp.deptno=dept.deptno;

Key-preserved table

A table is key-preserved if every key of the table can also be a key of the result of the join, so, a key-preserved table has its keys preserved through a join.

Criteria to be a key-preserved table

View should be based on more than one table and should be a join view

To satisfy key-preserved table at least one column should be a PRIMARY KEY in the join statement

Example:

CREATE VIEW myview AS SELECT empno, ename, dname, dept.deptno

FROM emp, dept WHERE emp.deptno=dept.deptno;

In the above example, table emp is a key-preserved table and table dept is a non-key-preserved table.

Following will the output when you will select from the view called myview:

Rules for DML statements on Join View

Any INSERT, UPDATE or DELETE statement a join view can modify only one underlying base table i.e., the emp table.

Examples:

INSERT INTO myview(empno, ename) VALUES(5678,JOHN);

UPDATE myview SET ename = McGILL WHERE empno=5678;

DELETE FROM myview WHERE ename=McGILL;

If we try to insert a row into the non-key-preserved table dept with the following statement:

INSERT INTO myview(deptno, dname) VALUES(50,PRODUCTION);

The statement would failed with an ORA-01776 error (can not modify more than one base table through a view)

UPDATE myview SET dname=ADMIN WHERE deptno=10;

This statement fails with an ORA-01779 error (can not modify a column which maps to a non-key-preserved table)

Dropping a view

The DROP VIEW command is used to remove a view from the database.Example:

DROP VIEW myview;

Working with Sequences

An Oracle SEQUENCE is a named sequential number generator. SEQUENCE are often used for artificial keys or to order rows that otherwise have no order. A SEQUENCE can be configured to increase or decrease.

A SEQUENCE can have the following parameters:

KEYWORDDESCRIPTION

START WITHDefines the 1st number that the sequence will generate. The default is 1.

INCREAMENT BYDefines the increase or decrease for subsequently generated number.

MINVALUEThe lowest number the sequence will generate. This is the bounding value in the decreasing sequence. The default MINVALUE is the keyword NOMINVALUE, which translates 1 for an increasing sequence and to minus -1026 for a decreasing sequence.

MAXVALUEThe largest number the sequence will generate. This is the bounding value by default for the increasing sequence. The default MAXVALUE is the keyword NOMAXVALUE, which translates to 1027 for an increasing sequence and to minus -1 for a decreasing sequence.

CYCLEConfigures the sequence to repeat numbers after reaching the bounding values.

When you create the sequence the START WITH value must be equal to or greater than MINVALUE. To access the next number in the SEQUENCE, you simply select from it, using the pseudo-column NEXTVAL. To get the last SEQUENCE number that your session has generated, you select from it using the pseudo-column CURRVAL. If your session has not yet generated a new sequence number, CURRVAL will be un-defined.

To Create a SEQUENCE:

CREATE SEQUENCE sq START WITH 1 INCREAMENT BY 5 MAXVALUE 50;

To fetch the NEXTVAL from a SEQUENCE:

SELECT sq.NEXTVAL FROM dual;

To fetch the CURRVAL from a SEQUENCE:

SELECT sq.CURRVAL FROM dual;

To alter a SEQUENCE:

ALTER SEQUENCE sq INCREAMENT BY 2;

To drop a SEQUENCE:

DROP SEQUENCE sq;

(Snapshots

DataBase Security and Privileges

Grant Command

Revoke Command

Application Privilege Management

Oracle provides three standard ROLEs:

Commit and RollBack

Implicit COMMIT

Auto ROLLBACK

Savepoint

(Objectives


Understand how to use GRANT command

Understand how to use REVOKE command

Assign and grant privileges to other users on database objects

Understand how to maintain database objects

Understand different transaction processing options

DataBase Security and Privileges

SQL is mostly executed in environments that require to recognize to differentiate between the various users of the system.

Each user in an Oracle database has a specific authorization.

Commands are interpreted and permitted (or prohibited) on the basis of information associated with the authorization associated with the ID of the user issuing the command.

The database administrator creates the users and assigns the privileges.

Privileges determine whether or not a user can execute a given command or a command when acting on specific groups of data.

Grant Command

The GRANT command is used to grant access to the database. A user can GRANT access to his/her database objects to another objects.

The syntax for GRANT command:

GRANT TO ;

GRANT

ON TO [WITH GRANT OPTION];

All tables, views, sequences that a user creates are owned by the user itself. Only the creator or DBA can access it.

The specifies the system level privileges to be granted to the users or roles (discussed later). This includes CREATE/ALTER/DROP any object of the system.

The specifies the actions such as SELECT, INSERT, DELETE, UPDATE, ALTER for tables.

indicates all the privileges. The privileges can be granted to the different users by specifying their names or to all users by using the PUBLIC option.

The WITH GRANT OPTION clause allows the recipient user to give further grant on the objects.

Examples:

GRANT ALL ON emp TO PUBLIC;

GRANT SELECT ON emp TO user1;

GRANT SELECT, INSERT ON emp TO user1, user2;

Revoke Command

Using REVOKE command a user can withdraw the privileges which has been granted earlier.Syntax:

REVOKE FROM

REVOKE ON FROM

Examples:

REVOKE ALL ON emp FROM PUBLIC;

REVOKE SELECT ON emp FROM user1;

REVOKE SELECT,INSERT ON emp FROM user1, user2;

Application Privilege Management

Roles are used to simplify the administrative tusks involved in the management of privileges.

Role is a collection of system privileges.

The syntax for creating ROLE is:

CREATE ROLE ;

Example:

CREATE ROLE myroll;

GRANT SELECT, INSERT ON emp TO myroll;

GRANT myroll TO user3;

Oracle provides three standard ROLEs:

CONNECT This ROLE only allows to use Oracle.

RESOURCE This ROLE only allows to create Oracle objects.

DBA This ROLE has the system privileges; such as Creating user, database.

When you are creating a new user, you must grant CONNECT and RESOURCE role to the newly created user.

Commit and RollBack

The COMMIT command is used to make changes to the data, permanently.

The ROLLBACK command is used to discard parts of all work the user has done in the current transaction.

SAVEPOINT statement are used to discard or commit all the changes up to a point.

SQL *Plus has the facility to automatically commit all the transactions without explicitly issuing the COMMIT command.

SET AUTOCOMMIT ONEnables autocommit feature.

SET AUTOCOMMIT OFFIs the default and disables the autocommit feature.

Implicit COMMIT

The actions that will force a commit to occur, even without issuing the COMMIT command are:

Exiting SQL *Plus

Creating any objects

Granting or Revoking resources

Altering objects

Connecting or disconnecting from Oracle

Auto ROLLBACK

After completion of any DML statement, if the user experiences serious difficulty such as: Hardware failure and no explicit COMMIT is made, Oracle will automatically rollback all un-committed work.

If there is no explicit COMMIT made and if the AUTOCOMMIT mode set to OFF then after the normal shut-down the server will commit all the un-committed transaction.

Savepoint

SAVEPOINT identifies a point in a transaction to which one can later rollback with the ROLLBACK statement. It is helpful when a transaction contain a large number of SQL statement and the user wants to commit only once when all are done.

If required one can rollback to a particular transaction. It works in a Last In Fast Out basis.

Example:

INSERT INTO dept VALUES(60,PURCHASE,DELHI);

SAVEPOINT sp1;

UPDATE emp SET deptno=60 WHERE ename=SMITH;

ROLLBACK TO SAVEPOINT sp1;

The ROLLBACK statement will undo the updation only. All transaction before the savepoint sp1 will remain unchanged, but not yet committed.

(Snapshots

Introduction to PL/SQL

Advantages of PL/SQL

PL/SQL Architecture

PL/SQL Block Structure

Named and Anonymous block

Conditional and Iterative Control

IF THEN

IF THENELSE

IF THENELSIF

LOOPEND LOOP

WHILELOOP

FORLOOP

SQL within PL/SQL

Writing a PL/SQL code

Composite Data Types

PL/SQL Records

Record Assignment

PL/SQL TABLES

(Objectives


Understand PL/SQL block structure and architecture

Understand the Conditional and iterative control

IF THEN

IF THENELSE

IF THENELSIF

LOOPEND LOOP

WHILELOOP

FORLOOP

Understand how to use SQL within PL/SQL

Understand How to write PL/SQL code

Understand Composite Datatype

Introduction to PL/SQL

PL/SQL is the procedural extension to the non-procedural SQL Combines data manipulation power of SQL and procedural power of standard procedural language

Provides performance improvements through blocking of RDBMS calls

Integrates well with SQL *Plus and other Application Development products of Oracle

Supports sub-programming features such as Procedures and Functions

PL/SQL is an extension to non-procedural SQL. It includes many features and designs of programming language. It combines the data manipulating power of SQL with the data processing power of procedural language. The PL/SQL engine resides within Oracle server so it is available from any application development tool that supports PL/SQL.

Advantages of PL/SQL

PL/SQL is a high performance transaction processing language. It is portable to any Oracle environment and supports all SQL data manipulation commands.

PL/SQL supports all SQL data types and all SQL functions. It also lets you use all Oracle object types. PL/SQL block can be named and stored in a Oracle server and reused as required in other PL/SQL program or from the SQL command line.

Security on PL/SQL structures stored in the server can be managed using the Oracle database objects syntax. You can grant and revoke privileges on these stored PL/SQL program to and from other user in the database.

PL/SQL code can be written using any ASCII text editor. So, it is portable to operating environment in which Oracle runs.

PL/SQL Architecture

PL/SQL Block Structure

PL/SQL block structured language. The units that constitute a PL/SQL program are logical blocks. A PL/SQL may contain one or more blocks. Each block may be divided into three sections as follows:

Declaration Section This section contains the data type and initial value of all variables and constant used in the executable section of the block. This section begins with the keyword DECLARE. This is an optional section. This section also declares CURSORs and used define EXCEPTIONs.

Executable Section This section is mandatory section in the PL/SQL block. This section begins with the keyword BEGIN. All the executable statements are given in this section. This section can also have other PL/SQL blocks inside.

Exception Section This section is an optional section, which has executable statement to handle an exception or error.

Here is the structure of a complete PL/SQL block:

[DECLARE]

-- Declaration Statements

BEGIN

-- Executable Statements

[EXCEPTION]

-- Exception Statements

END;

Each statement or declaration in a PL/SQL block is terminated with a semicolon. A statement may be broken down into multiple lines for readability, and the semicolon marks the end of the statement. More than one statement can appear in one line, separated by a semicolon. A single line of comment is preceded by two hyphens(--). A set of comments can be enclosed in /* and */.

Named and Anonymous block

A Pl/SQL block can be a Named block or an Anonymous block. Anonymous blocks can be used in the server side or in the client side. A Named block may appear in the declaration part of another block.

Conditional and Iterative Control

Control structures are lines of code that control the flow of the PL/SQL program. PL/SQL supports both conditional and iterative control structures.

Conditional and decision-control structures are used to perform an operation or statement based on the outcome of another statement or expression.

IFTHENELSEEND IF statement let you say, If this is true then do this; otherwise do that. Iterative control structure perform one or more statements repeatedly, either a certain number of times or until a condition is met. There are three forms of iterative structure.

LOOP

WHILELOOP

FORLOOP

Syntax and Usage

IF THEN

The IF statement evaluates a condition, and if the condition is satisfied, a set of statement are executed.

IF THEN

Statement 1;

Statement 2;

END IF;

The statements are executed only if the result of the condition is TRUE. The condition always evaluates to a Boolean result of TRUE/FALSE.

Example :

DECLARE

no NUMBER;

BEGIN

no := &no;

IF no>100 THEN

DBMS_OUTPUT.PUT_LINE ( You got 100 points!!!!!!!!);

END IF;

DBMS_OUTPUT.PUT_LINE ( TRY AGAIN!!!!!!!);

END;

IF THENELSE

This is similar to IFTHEN statement but a set of statements can be executed if the condition evaluates to FALSE or NULL.

IF THEN

Statement 1;

ELSE

Statement 2;

END IF;

The statement between THEN and ELSE are executed only if the result of the condition is TRUE, and the statement between ELSE and END IF are executed only if the result of the condition is FALSE.

Example :

DECLARE

no NUMBER;

BEGIN

no := &no;

IF no>100 THEN

DBMS_OUTPUT.PUT_LINE ( You got 100 points!!!!!!!!);

ELSE

DBMS_OUTPUT.PUT_LINE ( TRY AGAIN!!!!!!!);

END IF;

END;

IF THENELSIFUse this structure if you need to select an action from several mutually exclusive conditions.

IF THEN

Statement 1;

ELSIF THEN

Statement 2;

ELSE

Statement 3;

END IF;

If conditon1 is TRUE then statement1 will executes otherwise it will check condition2. If condition2 is TRUE then statement2 executes otherwise statement3 will executes.

Example :

DECLARE

age NUMBER;

BEGIN

age:=&age;

IF (age>=60) THEN

DBMS_OUTPUT.PUT_LINE('Age more than equal to 60 !!!');

ELSIF(age>=40 and age=30 and age100) THEN

EXIT;

END IF;

END LOOP;

END;

WHILELOOP

This loop has a condition associated with it. The condition is evaluate, and, if the result is TRUE, the statements inside the loop are executed. If the condition is FALSE, execution continues from the next statement to END LOOP.

WHILE

LOOP

Statements;

END LOOP;

Example :

DECLARE

no NUMBER :=10;

BEGIN

WHILE ( no THEN

RAISE my_exception2;

EXCEPTION

WHEN my_exception1 THEN

Statements;

END;

EXCEPTION


Statements;

END;

Statements;

If there is no enclosing block for the current block, the exception si passed back to the environment that invoked the PL/SQL program.

DECLARE

my_exception1 EXCEPTION;



BEGIN

Statements;

BEGIN

IF < condition1 > THEN

RAISE my_exception3;

EXCEPTION


Statements;

END;

EXCEPTION


Statements;

END;

Only one exception at a time can be active in the exception handling part of a block. Therefore, if an exception is raised inside a handler, the block that encloses the current block is the first block searched to find a handler for the newly raised exception.

Example 1 :

DECLARE

Enoemp.empno%type;

Enmemp.ename%type;

Esalemp.sal%type;

HsalEXCEPTION;

LsalEXCEPTION;

BEGIN

Eno := &Eno;

SELECT ename, sal into Enm, Esal FROM emp WHERE Eno = empno;

IF ( Esal 4000 ) THEN

RAISE Has;

END IF;

DBMS_OUTPUT.PUT_LINE(Enm|| ||Esal);

EXCEPTION

WHEN Lsal THEN

DBMS_OUTPUT.PUT_LINE(The salary is too Low!);

WHEN Hsal THEN

DBMS_OUTPUT.PUT_LINE(The salary is Standard);

WHEN NO_DATA_FOUND THEN

DBMS_OUTPUT.PUT_LINE(Invalid Employee Code!!!);

END;

Example 2 :

DECLARE

BEGIN

FOR i IN ( SELECT empno, ename, sal FROM emp)

LOOP

DECLARE

Lsal EXCEPTION;

BEGIN

IF ( i.sal

( [ mode ] , . )

IS | AS

[ local declaration ]

BEGIN

Executable statements

[ EXCEPTION

exception handlers ]

END [ PROCEDURE_NAME ];

Calling a Procedure

To call the procedure from a block, the command is

PROCEDURE_NAME ( );

To invoked from the SQL prompt using the EXECUTE command

EXECUTE PROCEDURE_NAME( );

Example :

CREATE OR REPLACE PROCEDUR PR1 ( Eno NUMBER )

IS

Enmemp.ename%TYPE;

Esalemp.sal%TYPE;

BEGIN

SELECT ename,sal into Enm, Esal FROM emp WHERE Eno := emp.empno;

DBMS_OUTPUT.PUT_LINE ( Eno|| ||Enm|| ||esal);

EXCEPTION


DBMS_OUTPUT.PUT_LINE (Invalid Employee Number !!!);

END;

Actual Vs. Formal parameter

The variable or expressions referenced in the parameter list of a subprogram all are actual parameters

The variables declared in a subprogram specification and referenced in the subprogram body are formal parameters

The actual parameter and its corresponding formal parameter must to compatible datatype

Argument Modes

Argument modes are used to define the behavior of formal parameters. There are three argument modes to be used with any subprograms.

IN The IN parameter lets the user pass values to the called subprogram. Inside the subprogram, the IN parameter acts like a constant; therefore, it cannot be modified.

OUT The OUT parameter lets the user return values to the called subprogram. Inside the subprogram, the OUT parameter acts like a un-initialized variable. Therefore, it cannot be assigned to another variable or to itself.

IN OUT The IN OUT parameter lets the user pass initial values to the called subprogram and returns updated values to the calling block.

Example 1:

Creating the Procedure :

CREATE OR REPLACE

PROCEDUR PR1 ( eno IN NUMBER, enm OUT VARCHAR2, esal OUT NUMBER )

IS

BEGIN

SELECT ename,sal into enm, esal FROM emp WHERE eno := emp.empno;

EXCEPTION


DBMS_OUTPUT.PUT_LINE (Invalid Employee Number !!!);

END;

Calling a Procedure :

DECLARE

Eno emp.empno%TYPE;

Enmemp.ename%TYPE;

Esalemp.sal%TYPE;

BEGIN

Eno := &Eno;

PR1 ( Eno, Enm, Esal );

DBMS_OUTPUT.PUT_LINE ( Eno|| ||Enm|| ||esal);

END;

Example 2 :

Creating a Procedure

CREATE OR REPLACE PROCEDURE ad(aa IN OUT NUMBER) IS

bb NUMBER;

cc NUMBER;

BEGIN

cc:=aa;

bb:=10;

DBMS_OUTPUT.PUT_LINE(The value from the calling program : ||cc);

aa:=bb;

END;

Calling a procedure

DECLARE

bb NUMBER;

BEGIN

bb:=5;

ad(bb);

DBMS_OUTPUT.PUT_LINE(The changed value : ||bb);

END;Functions

A Function is a sub-program that returns a value. A function must have return clause. The syntax for the function is:

CREATE [ OR REPLACE ] FUNCTION < function_name >

(, . ) RETURN

IS

[ local declaration ]

BEGIN

Executable statements;

[ EXCEPTION

exception handlers ]

END [ function_name ];

Like a procedure, a function has two parts; the specification and the body. The function specification begins with the keyword FUNCTION and ends with the RETURN clause, which specifies the datatype of the result value. The function is exactly same as procedure body. The RETURN statement immediately returns control to the caller environment. Execution then resumes with the statement following the sub-program call.

Example 1:

Specifying a function

CREATE OR REPLACE

FUNCTION fn1 ( esal NUMBER, rate NUMBER) RETURN NUMBER

IS

da NUMBER(8,2);

BEGIN

da:= esal*(rate/100);

RETURN da;

END;

Calling a function from SQL prompt

SELECT empno, ename, sal, fn1(sal,20) as DA FROM emp;

Calling function from PL/SQL block

DECLARE

eno emp.empno%TYPE;

enmemp.ename%TYPE;

esalemp.sal%TYPE;

rtNUMBER(2);

daNUMBER(8,2);

BEGIN

rt:=&rt;

eno := &eno;

SELECT empno, ename, esal INTO eno, enm, esal

FROM emp WHERE empno=eno;

da:=fn1(esal, rt);

DBMS_OUTPUT.PUT_LINE ( Eno|| ||Enm|| ||esal|| ||da);

END;

Stored Package

A Package is a database object that groups logically related PL/SQL objects. Package encapsulates related procedures, functions together as a logical unit in the database. Packages are made of two components; the specification and the body. A specification is the interface to applications and has declarative statements. The body of the package contains different procedures and functions.Package Specification

The specification is the interface to the application, it declares the procedures and functions. The package specification holds the public declarations, which are visible to the application.

Package Body

The body holds implementation details and private declaration, which are hidden from the application. The scope of these declarations is local to the package body. Unlike a package specification, the declarative part of a package body can contain sub-program bodies. Package can overload procedures and functions, declaring multiple programs with the same name. The correct program to be called is decided at runtime, based on the number or datatypes of the parameters. To create a package, you must first create the package specification. You cannot GRANT privileges on only one procedure or function within a package.

Advantages of package

Modularity

Packages encapsulates related procedures and functions together in a named PL/SQL module.

Easier application design

It is not important to compile the package body completely until the application is complete. When designing an application initially the information in the specification is required. A specification can be coded and compiled without its body. Once the specification has been compiled, stored sub-programs that reference the package can be compiled as well.

Information Hiding

The packages can be specified in which all sub-programs are public that is, visible and accessible or private that is hidden and in-accessible. By hiding implements details from users, integrity of package is protected.

Better Performance

The entire package is loaded into the memory when a procedure, within the package, is called for the first time. This reduce the un-necessary disk I/O and network traffic.

Specifying a package:

CREATE [OR REPLACE] PACKAGE AS

/* Procedures and function declarations */

END [ ];

Creating a package body:

CREATE [OR REPLACE] PACKAGE BODY AS

/* Private variable declarations

Sub-program bodies */

END [];

Example:

CREATE OR REPLACE PACKAGE pkg AS

PROCEDURE addition(a NUMBER, b NUMBER);

FUNCTION higher(a NUMBER, b NUMBER) RETURN NUMBER;

END pkg;

CREATE OR REPLACE PACKAGE BODY pkg AS

PROCEDURE addition(a NUMBER, b NUMBER)

IS

c NUMBER;

BEGIN

c:=a+b;

DBMS_OUTPUT.PUT_LINE(The resultant value is : || c);

END addition;

FUNCTION hiegher(a NUMBER, b NUMBER)

IS

c NUMBER;

BEGIN

IF (a>b) THEN

c:=a;

ELSE

c:=b;

END IF

RETURN c;

END higher;

END pkg;

Dropping Procedures, Function and Package

To drop a procedure the syntax is : DROP PROCEDURE ;

To drop a function the syntax is : DROP FUNCTION ;

To drop a package the syntax is : DROP PACKAGE ;

DataBase Trigger

Triggers are programs that are executed automatically in response to a change in the database. Triggers can be configured to fire, or execute, either before or after the triggering event. The events that can be hooked with triggers include the following.

DML events

DDL events

Database events

DML event triggers can be statement or row triggers. The DML statement trigger fires before or after the triggering statement. The DML row trigger fires before or after each row affected by the statement is changed. You can define multiple triggers for a single event and type, but there is no way to enforce the order in which these multiple triggers will fire.

Trigger Events

EventTrigger Description

INSERTFires whenever a row is inserted into the table or view.

UPDATEFires whenever a row is updated in the table or view.

DELETEFires whenever a row is deleted from a table or view.

CREATEFires whenever a CREATE statement adds a new object to the database.

ALTERFires whenever a ALTER statement changes an object in the database.

DROPFires whenever a DROP statement removes an object from the database.

The syntax for creating a trigger :

CREATE [ OR REPLACE ] TRIGGER

{ BEFORE | AFTER | INSTEAD OF }

ON { table_name | view name }

[ FOR EACH ROW [ WHEN ]]

trigger body

In case of tables BEFORE and AFTER are used. In case of views INSTEAD OF is used.

Example :

CREATE OR REPLACE TRIGGER t1

BEFORE INSERT OR UPDATE OF empno ON emp FOR EACH ROW

BEGIN

:new.ename := UP

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