Basics of JDBC Session 14.

Basics of JDBC

Session 14

Basics of JDBC / 2 of 23

Objectives

Describe ODBC Discuss what is JDBC Discuss why we need JDBC Describe the java.sql package in brief Discuss types of drivers Explain the anatomy of a JDBC program

Explain the concept of database connectivity


Database

Client/Server applications make extensive use of database programming

Activities may involve opening a connection, communicating with a database, executing SQL statements and retrieving query results

Standardized APIs are available that simplify database programming. Examples of these are ODBC and JDBC

A database contains data that is in an organized form


ODBC

Provides functions to insert, modify and delete data and obtain information from the database

Open DataBase Connectivity (ODBC) is an Application Programming Interface (API) provided by Microsoft for accessing databases


How ODBC connection takes place?

Application could be a GUI program Makes use of ODBC to interact with databases Driver Manager is part of Microsoft ODBC and is used to manage various drivers in the system

Application ODBC

InterfaceDriver

Manager

Access Driver

Oracle Driver

…

AccessDatabas

eOracle

Database

…


Need for JDBC

A literal translation of the ODBC C interface into a Java API would not be desirable

ODBC mixes simple and advanced features together and has complex options even for simple queries

A Java API like JDBC is needed in order to enable a “pure Java” solution

JDBC is portable JDBC is a standard interface for Java programmers

to access relational databases

ODBC uses a C interface that has lot of drawbacks


JDBC

Defines a set of API objects and methods to interact with databases

JDBC is a must for all Java applications that access data stored in external data providers like SQL Server, Oracle or Access

JDBC is a Java Database Connectivity API that is a part of the Java Enterprise API


JDBC - ODBC bridge Database Server

SQL Server

JDBC Driver Types (1)

ODBC is not readily convertible to Java Sun provides a bridge driver to access ODBC data

sources from JDBC This is called the JDBC-ODBC Bridge plus ODBC

driverDatabase Server

OracleODBC Driver

ODBC DriverDB-client

JDBC-ODBC Bridge plus ODBC Driver



JDBC calls are converted into calls on the client API for DBMS

This driver uses JavaNativeInterface(JNI) that calls the local database APIs

The Native APIs partly-Java driver calls the Native Database Library that accesses the database

This driver like the ODBC driver needs binary code on the client machine

Database ServerJDBC Driver (Java and Binary Code)

Vendor Specific ProtocolDB-client

Native API partly-Java Driver


JDBC Driver Types (3) Uses a networking protocol and middleware to

communicate with the server Server then translates the messages

communicated to DBMS specific function calls Specific protocol used depends on the vendor No need for client installation Allows access to multiple back-end databases

JDBC Driver (Pure Java

Driver)

Database Server SQL Server

Database Server

DB-client

JDBC-Net pure Java driver

Networking protocol & middleware



100% Java enabled and does not use CLI libraries Capable of communicating directly with the database Converts JDBC calls into network protocols such as

TCP/IP and other proprietary protocols used by DBMS directly

Since many of these protocols are proprietary, the database vendors themselves will be the primary source of usage

Database ServerJDBC Driver (Pure Java Driver)

Vendor Specific Protocol

DB-client

Native-protocol pure Java driver


JDBC architecture (1)

Java Program

JDBC Driver

Application Server

Database

SQL command Results



Application Layer – developer makes calls to database through SQL and retrieves results

Driver layer – handles all communication with a specific driver implementation

Four main Java interfaces that every Driver layer must implement are : Driver, Connection, Statement and ResultSet

The JDBC API interface comprises of two layers:



Application layer

Driver layer

Driver

Statement ResultSet

Connection

Implements Interfaces


JDBC components

Driver Manager – to load specific drivers for an application

Driver Data Source – User application interacts with

this to get results

Application – here the JDBC methods are used to execute SQL and get results


The java.sql package

These are contained in the java.sql package Classes included in this package are :

Date, DriverManager, DriverPropertyInfo, Time, TimeStamp, Types

Interfaces included are : Callable Statement, Connection,

DatabaseMetaData, Driver, PreparedStatement, ResultSet, ResultSetMetaData, Statement

JDBC API defines a set of interfaces and classes used for communicating with the database


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Creating a JDBC applicationBegin

Import the java.sql package

Load and Register the driver

Create a Connection object

Create a Statement object

Execute the statement

Close ConnectionEnd


Example

Output


Using SQL (1)

To find out the number of employees who joined together on the same day and whose job_id is equal to 5:

SELECT count(*) FROM Employee WHERE job_id=5 GROUP BY hire_date

To retrieve the name, phone, email and phone number from the table colleagues:

SELECT name, email, phone FROM colleagues


Using SQL (2)

Instead they return an integer representing the number of rows affected

Assume we need to add a new record – INSERT into COFFEE

VALUES(‘French_Roast’,00049,8.99,0,0)

SQL DML statements do not return the results as ResultSets


Using SQL (3)

Data Definition Language statements are used to create tables, add columns to the existing tables; delete tables and so on CREATE TABLE Emp(emp_name

VARCHAR(25),emp_no VARCHAR(4),emp_age number);

The LIKE operator is used with SQL statements to compare two strings SELECT * FROM employee WHERE emp_id LIKE

‘A%’


Example (1)


Example (2)

Output

Basics of JDBC Session 14.

Documents

Transcript of Basics of JDBC Session 14.