CSC 213 Database Management System 2 Credits Compulsory

Objectives:

At the end of the course, students should be able to:

I. Identify and explain different types and modules of database.

II. List the advantages and disadvantages of database models.

III. Explain data storage, retrieval, security, and integrity.

IV. Use database management system to store, update, insert, retrieve and delete records.

V. Identify and explain at least three Dbase administrative functions.

Course Content:

An Overview Database Management

Nature of Database Management system (DBMS)

Different types of DBMS

Models of Database: Network, Hierarchical, Relational, Distributed

Advantages and Disadvantages

Concept of Fields, Records, Access Methods

Data Storage and Retrieval

Data Security and Integrity

Database Administration (DBA)

Methods of Data Organization

Data capturing

Query, sorting, Report generation

Wizard and Design view etc

Application in student record, payroll, inventory control etc Intensive Practice with Relational

Data base

Overview of Database

A Database is a collection of related data organised in a way that data can be easily accessed,

managed and updated. Any piece of information can be a data, for example name of your school.

Database is actually a place where related piece of information is stored and various operations

can be performed on it.

For example, a university database might contain information about the following:

• Entities such as students, faculty, courses, and classrooms.

• Relationships between entities, such as students' enrollment in courses, faculty teaching

courses, and the use of rooms for courses.

DBMS

A DBMS (Database Management System)is software that allows creation, definition and

manipulation of database. DBMS is actually a tool used to perform any kind of operation on data

in database. DBMS also provides protection and security to database. It maintains data

consistency in case of multiple users. Here are some examples of popular DBMS, MySql,

Oracle, Sybase, Microsoft Access and IBM DB2 etc.

The alternative to using a DBMS is to use ad-hoc approaches that do not carry over from one

application to another; for example, to store the data in files and write application-specific code

to manage it.

Components of Database System

The database system can be divided into four components.

• Users: Users may be of various types such as DB administrator, System developer and

End users.

• Database application : Database application may be Personal, Departmental, Enterprise

and Internal

• DBMS: Software that allow users to define, create and manages database access, Ex:

MySql, Oracle etc.

• Database: Collection of logical data.

The functions performed by a typical DBMS are the following:

1. Data Definition: The DBMS provides functions to define the structure of the data in the

application. These include defining and modifying the record structure, the type and size

of fields and the various constraints/conditions to be satisfied by the data in each field.

2. Data Manipulation: Once the data structure is defined, data needs to be inserted, modified

or deleted. The functions which perform these operations are also part of the DBMS. This

function can handle planned and unplanned data manipulation needs. Planned queries are

those which form part of the application. Unplanned queries are ad-hoc queries which are

performed on a need basis.

3. Data Security & Integrity: The DBMS contains functions which handle the security and

integrity of data in the application. These can be easily invoked by the application and

hence the application programmer need not code these functions in his/her programs.

4. Data Recovery & Concurrency: Recovery of data after a system failure and concurrent

access of records by multiple users are also handled by the DBMS.

5. Data Dictionary Maintenance: Maintaining the Data Dictionary which contains the data

definition of the application is also one of the functions of a DBMS.

6. Performance: Optimizing the performance of the queries is one of the important functions

of a DBMS. Hence the DBMS has a set of programs forming the Query Optimizer which

evaluates the different implementations of a query and chooses the best among them.

ADVANTAGES OF A DBMS

Using a DBMS to manage data has many advantages:

• Data independence: Application programs should be as independent as possible from

details of data representation and storage. The DBMS can provide an abstract view of the

data to insulate application code from such details.

• Efficient data access: A DBMS utilizes a variety of sophisticated techniques to store and

retrieve data efficiently. This feature is especially important if the data is stored on

external storage devices.

• Data integrity and security: If data is always accessed through the DBMS, the DBMS

can enforce integrity constraints on the data. For example, before inserting salary

information for an employee, the DBMS can check that the department budget is not

exceeded. Also, the DBMS can enforce access controls that govern what data is visible to

different classes of users.

• Data administration: When several users share the data, centralizing the administration

of data can offer significant improvements. Experienced professionals, who understand

the nature of the data being managed, and how different groups of users use it, can be

responsible for organizing the data representation to minimize redundancy and for fine-

tuning the storage of the data to make retrieval efficient.

• Concurrent access and crash recovery: A DBMS schedules concurrent accesses to the

data in such a manner that users can think of the data as being accessed by only one user

at a time. Further, the DBMS protects users from the effects of system failures.

• Reduced application development time: Clearly, the DBMS supports many important

functions that are common to many applications accessing data stored in the DBMS.

This, in conjunction with the high-level interface to the data, facilitates quick

development of applications. Such applications are also likely to be more robust than

applications developed from scratch because many important tasks are handled by the

DBMS instead of being implemented by the application.

DISADVANTAGES OF A DBMS

Given all these advantages, is there ever a reason not to use a DBMS?

• Complexity: A DBMS is a complex piece of software, optimized for certain kinds of

workloads (e.g., answering complex queries or handling many concurrent requests), and

its performance may not be adequate for certain specialized applications. Examples

include applications with tight real-time constraints or applications with just a few well-

defined critical operations for which efficient custom code must be written.

• Application data requirement: Another reason for not using a DBMS is that an

application may need to manipulate the data in ways not supported by the query

language. In such a situation, the abstract view of the data presented by the DBMS does

not match the application's needs, and actually gets in the way. As an example, relational

databases do not support flexible analysis of text data (although vendors are now

extending their products in this direction). If specialized performance or data

manipulation requirements are central to an application, the application may choose not

to use a DBMS, especially if the added benefits of a DBMS (e.g., flexible querying,

security, concurrent access, and crash recovery) are not required.

• Costly

• Large in size

NATURE OF DATABASE MANAGEMENT SYSTEM (DBMS)

1.Self-describing nature of the database system: A DBMS catalog stores the description of the

database. The description is called metadata. This allows the DBMS software to work with

different databases.

2.Insulation between program and data:It is called program-data independence.It allows

changing the data storage structure and operations without changing the DBMS access program.

3.Data Abstraction: A data model is used to store hide storage details and present the user with

a conceptual view of the database.

4.Support the multiple views of the data: Each user may see a different view of the database,

which describes only the data of interest to that user.

5.Sharing of data and multiuser transaction processing:It says that it allows a set of

concurrent users to retrieve and to update the Database.Concurrency with the DBMS guarantees

that each transaction is correctly executed or completely aborted.

DIFFERENT TYPES OF DBMS

1. Numeric and Textual databases

2. Multimedia databases

3. Geographic information system databases

4. Data warehouses

5. Real and active databases

Data Types

A data type is a type of data. ... They may also be more specific types, such as dates, text,

memo, and Number formats. Some programming languages require the programmer to define

the data type of a variable before assigning it a value.

Data Type Description

AutoNumber An AutoNumber field creates unique values automatically when Access creates a

new record. The AutoNumber field is primarily used for Primary Keys in Access.

Text A Text field can contain values that are text, numeric or a combination of both. A

text field can contain a maximum length of 255 characters.

Memo

A much larger version of the text field, allowing storage of up to 2 GB of data. A

new feature of the Microsoft Access Memo field is that it now supports rich text

formatting.

Number The Number field can store numeric values up to 16 bytes of data.

Date/Time The Date/Time field allows storage of date and time information. The date/time

field now also includes the Auto Calendar feature.

Currency The Currency data type stores values in a monetary format. This can be used with

financial data as 8-byte numbers with precision to four decimal places.

Yes/No Boolean data storage of true/false values.

OLE Object

The OLE Object field stores images, documents, graphs etc. from Office and

Windows based programs. The maximum data size is 2 GB, although this will

slow down a database.

Hyperlink The Hyperlink field type is used to store web addresses. This has a maximum size

limit of 1 GB of data.

Attachment The Attachment field type is used to store images, spreadsheet files, documents,

charts and other types of supported files to the records in your database. This is a

new feature that has been introduced with Microsoft Access 2007.

MODELS OF DATABASE: NETWOORK, HIERRACHICAL, RELATIONAL AND

DISTRIBUTED

What is database model? A database model is a type of data model that determines the logical

structure of a database and fundamentally determines in which manner data can be stored,

organized, and manipulated. The most popular example of a database model is the relational

model, which uses a table-based format.

HIERARCHICAL MODEL

In a hierarchical model, data is organized into a tree-like structure, implying a single parent for

each record. A sort field keeps sibling records in a particular order. Hierarchical structures were

widely used in the early mainframe database management systems, such as the Information

Management System (IMS) by IBM, and now describe the structure of XML documents. This

structure allows one one-to-many relationship between two types of data. This structure is very

efficient to describe many relationships in the real world; recipes, table of contents, ordering of

paragraphs/verses, any nested and sorted information.

Network model

The network model expands upon the hierarchical structure, allowing many-to-many

relationships in a tree-like structure that allows multiple parents. It was most popular before

being replaced by the relational model, and is defined by the CODASYL specification.

The network model organizes data using two fundamental concepts, called records and sets.

Records contain fields (which may be organized hierarchically, as in the programming language

COBOL). Sets (not to be confused with mathematical sets) define one-to-many relationships

between records: one owner, many members. A record may be an owner in any number of sets,

and a member in any number of sets.

Relational model

The relational model was introduced by E.F. Codd in 1970 as a way to make database

management systems more independent of any particular application. It is a mathematical model

defined in terms of predicate logic and set theory, and systems implementing it have been used

by mainframe, midrange and microcomputer systems.

The products that are generally referred to as relational databases in fact implement a model that

is only an approximation to the mathematical model defined by Codd. Three key terms are used

extensively in relational database models: relations, attributes, and domains. A relation is a table

with columns and rows. The named columns of the relation are called attributes, and the domain

is the set of values the attributes are allowed to take.

CONCEPTS

PRIMARY KEY: A primary key, also called a primary keyword, is a key in a relational

database that is unique for each record. It is a unique identifier, such as a driver license number,

telephone number (including area code), or vehicle identification number (VIN). A relational

database must always have one and only one primary key.

FOREIGN KEY: In the context of relational databases, a foreign key is a field (or collection of

fields) in one table that uniquely identifies a row of another table or the same table. In simpler

words, the foreign key is defined in a second table, but it refers to the primary key in the first

table.

FIELDS: Fields are the smallest units of information you can access. In spreadsheets, fields are

called cells.

RECORDS: A collection of fields is called a record.

ACCESS METHODS:

DATA STORAGE AND RETRIEVAL

WHAT IS DATA STORAGE?

Computer data storage, often called storage or memory, is a technology consisting of computer

components and recording media used to retain digital data. It is a core function and

fundamental component of computers. The central processing unit (CPU) of a computer is what

manipulates data by performing computations.

WHAT IS DATA RETRIEVAL?

Data retrieval means obtaining data from a database management system such as ODBMS. In

this case, it is considered that data is represented in a structured way, and there is no ambiguity

in data. In order to retrieve the desired data the user present a set of criteria by a query.

DATA SECURITY AND INTEGRITY

DATA SECURITY?

Data security refers to protective digital privacy measures that are applied to prevent

unauthorized access to computers, databases and websites. Data security also protects data from

corruption. Data security is the main priority for organizations of every size and genre.

Data security is also known as information security (IS) or computer security.

Examples of data security technologies include software/hardware disk encryption, backups, data

masking and data erasure.

A key data security technology measure is scrambling, where digital data, software/hardware,

and hard drives are scrambled and rendered unreadable to unauthorized users and hackers.

DATA INTEGRITY?

Data integrity refers to the overall completeness, accuracy and consistency of data. This can be

indicated by the absence of alteration between two instances or between two updates of a data

record, meaning data is intact and unchanged.

DATABASE ADMINISTRATION (DBA)

Database administration is the function of managing and maintaining database management

systems (DBMS) software. Mainstream DBMS software such as Oracle, IBM DB2 and

Microsoft SQL Server need ongoing management.

Database administrators (DBAs) use specialized software to store and organize data.

The role may include capacity planning, installation, configuration, database design, migration,

performance monitoring, security, troubleshooting, as well as backup and data recovery.

METHODS OF DATA ORGANIZATION

DEFINATION: Data organization, in broad terms, refers to the method of classifying and

organizing data sets to make them more useful. Some IT experts apply this primarily to physical

records, although some types of data organization can also be applied to digital records.

METHODS

There are many ways that IT professionals work on the principle of data organization. Many of

these are classified under the more general heading of "data management." For example, re-

ordering or analyzing the arrangement of data items in a physical record is part of data

organization.

One other main component of enterprise data organization is the analysis of relatively structured

and unstructured data. Structured data is comprised of data in tables that can be easily integrated

into a database and, from there, fed into analytics software or other particular applications.

Unstructured data is data that is raw and unformatted, the kind of data that you find in a simple

text document, where names, dates and other pieces of information are scattered throughout

random paragraphs. Experts have developed tech tools and resources to handle relatively

unstructured data and integrate it into a holistic data environment.

Businesses adopt data organization strategies in order to make better use of the data assets that

they have in a world where data sets represent some of the most valuable assets held by

enterprises across many different industries. Executives and other professionals may focus on

data organization as a component of a comprehensive strategy to streamline business processes,

get better business intelligence and generally improve a business model.

DATA CAPTURING

In (Computer Science) any process for converting information into a form that can be handled by

a computer.

Input of data, not as a direct result of data entry but instead as a result of performing a different

but related activity. Barcode reader equipped supermarket checkout counters, for example,

capture inventory related data while recording a sale.

QUERY, SORTING, REPORT GENERATION

QUERY

A query is a request for information from a database. There are three general methods for posing

queries:

Choosingparameters from a menu: In this method, the database system presents a list

of parameters from which you can choose. This is perhaps the easiest way to pose a query

because the menus guide you, but it is also the least flexible.

Query by example (QBE): In this method, the system presents a blank record and lets

you specify the fields and values that define the query.

Query language: Many database systems require you to make requests for information

in the form of a stylized query that must be written in a special query language. This is

the most complex method because it forces you to learn a specialized language, but it is

also the most powerful.

SORTING

The fields of a database can be sorted or rearranged in a number of ways: Ascending order --

Arrangement of data from lowest to highest in sequence. Descending order -- Arrangement of

sorted data from highest to lowest in sequence.

REPORT GENERATION

A report generator is a computer program whose purpose is to take data from a source such as a

database, XML stream or a spreadsheet, and use it to produce a document in a format which

satisfies a particular human readership.