Java Database Connectivity

By M.YAMUNA DEVI

CSE Department , 10AG1AO568

CONTENTSIntroduction.Importance of databases.Jdbc.Jdbc api,architecture.Jdbc key components with steps.Overview of querying a db with stages.Advantages and disadvantages.Conclusion.

Introduction

Why Java??

>Write once, run anywhere> Multiple client and server platforms

> Database independence> Java can access any database vendor

> Ease of administration

Importance of databases:

we can store our data permanently by using file concept. If we are using file concept we have some drawbacks.

•.if we want to use file concept we need to know about IO package concept and can store small amount of data.

•Inserting , deleting, updating in files it takes more time.

•It does not support query language

•In files we store data in the form of text or objects.

to overcome all these problems we go for database software

In database software the data will be stored permanent it supports query language.

it takes less time for inserting ,deleting ,updating ,retrieve .

in database s/w the data will be stored in table storing in the form of rows and columns.

some of the database software are 1)oracle2)mysql3)sql server4)DB2

JDBC > odbc is a standard or open application programming

interface (API) for accessing a database.

Handles these requests and converts it into a request understandable by an individual database system.

Java API for connecting programs written in Java to the data in relational databases

The standard defined by Sun Microsystems, allowing individual providers to implement and extend the standard with their own JDBC drivers.

JDBC Architecture> Tasks of JDBC:

1) establishes a connection with a database 2) sends SQL statements 3) processes the results

JDBC key components:

Driver Manager , Connection , Statement , Result Set

• Driver Manager handles communication with different drivers that conform to JDBC Driver API

• The static class Driver Manager manages the loaded drivers and contains methods for accessing connections to the databases JDBC Driver Manager

Four steps in creating a database application

Step 1: load a database driver Step 2: make a database connection Step 3: create and execute SQL statement Step 4: process the result set , if necessary

Step 1: Loading a Driver

•Loading a driver requires class name of the driver•For JDBC-ODBC driver the class name is: sun. jdbc.Odbc .JdbcOdbcDriver try { Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”); }•The class definition of the driver is loaded using forName static method of the class Class (in package java.lang )

• catch (Exception e) { System.out.println(e);}

Step 2: Opening a Database Connection

• Connection is an interface defined in java.sql package. A Connection object represents a connection with the database.

The interface has methods to create statements which can be used to manipulate the database.Connection cn=DriverManager.getConnection(“jdbc:odbc:ora”,”yamuna”,”ace”);

Step 3: Creating Statement & executing SQL Statements

Connection objects can be used to create statement objects. Statement = cn.createStatement(); Statement is an interface that contains methods for executing SQL queries Like executeUpdate()-insert,delet,updateFor selection we refer executeQuery()

Step4:Retrieving the data from db

Individual column fields can be retrieved using the get methods within the ResultSet.String qry=“select *from employs”;ResultSet rs=stmt.executeQuery(qry); String id=rs.getString(1);Resultset is the return type of executeQuery().Columns may be specified by their field name or by their index.

Overview of Querying a Database With JDBC

Query

Close

Connect

Processresults

Stage 1: Connect

Query

Close

Connect

Processresults

Register the driver

Connect to the database

Stage 2: Query

Close

Connect

Query Create a statement

Processresults

Query the database

Stage 3: Process Results

Close

QueryStep through the results

Processresults

Assign results to Java variables

Connect

Stage 4: Close

Connect

Query

Processresults

Close

Close the result set

Close the statement

Close the connection

Advantages

1) Can read any database if proper drivers are installed.                    2) Query and Stored procedure supported.

Disadvantages 1) Correct drivers need to be deployed for each type                            of database                             2) Cannot update or insert multiple tables with                              sequence. ( Sequence is always random) 

ConclusionJDBC provides API or Protocol to interact with different

databases.With the help of JDBC driver we can connect with different types of databasesThis technology is an API for the java programming language that defines how a client may access a database. It provides methods for querying and updating data in a database. JDBC is oriented towards relational databases. A JDBC-to-ODBC bridge enables connections to any ODBC-accessible data source in the JVM host environment.

 

References

http://www.oracle.com/technetork/java/javase/jdbc/index.html

.http://docs.oracle.com/javase/tutorial/jdbc/http://www.webopedia.com/TERM/J/JDBC.htmlhttp://infolab.stanford.edu/~ullman/fcdb/oracle/or-jdbc.html

Thank You !!!

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