JDBC - I (Java Data base Connectivity)

 

   JDBC-1

Networking Basics

JDBC, often known as Java Database Connectivity, provides a Java API for updating and querying relational databases using Structured Query Language(SQL).

Different type of JDBC Driver

vJDBC - ODBC Bridge

           -Provides a Java bridge to ODBC

vType 2 Native - API (Partly Java)

-uses native code to access the Dob with a thin Java wrapper

vType 3 Net - protocol (All Java)

- defines a generic network protocol that    interfaces with some middle ware that accesses the DB

vType 4 Native-protocol (All Java)

  - written entirely in Java

ODBC

Open Database Connectivity: is used as an interface between Windows applications and different type of databases.

When using Java under Windows it is not possible to access existing ODBC Driver because ODBC  was created using C with pointers. JDBC-ODBC Driver is used as an interface between Java Applications and ODBC Driver.

INTRODUCTION TO DATABASE

A database is a collection of tables or relations. Each table contains set of rows which contains information in the form of Row and Column. Each column contains meaningful information of specific type.

SQL-Structured Query Language

     SQL is a standard language to manipulate database.

Important SQL Statements

 

1.To Create Table

        CREATE: TABLE STUDENT (NAME Varchar(32),COURSE varchar(12),FEES

2.To retrieve information

        SELECT*FROM STUDENT WHERE COURSE = 'JAVA'

3. To insert information

         INSERT INTO STUDENT VALUES ('Kumar','JAVA',4800.0,1001')

 4. To update information

         UPDATE STUDENT SET COURSE ='DJP'WHERE STUDNO =1001

5. To update information

       DELETE * FROM STUDENT WHERE STUDNO =1001

Six Basic Steps in Using JDBC

1. Load the driver

If you want to use the JDBC - ODBC Bridge driver, the following code will load it:

     Class.for Name("sun.jdbc.odbc.JdbcOdbcDriver");

You do not need to create an instance of a driver and registger it with the DriverManager because calling the method Class. for Name will do that for you automatically.

2.Establish the Connection

     Connection con = DricverManager.get Coonection(url,  "myLogin", "myPassword");

The getConnection method of Driver Manager class establishes a connectin to the specified ODBC data source name specified in the URL. For JDBC-ODBC bridge driver,the JDBC URL Will jdbc: odbc:data Source Name. The remaining two arguments are user name and password of the database.

3. Create a Statement object

     Statement stmt = con.createStatement();

A Statement object is used to send SQL statements to the Databa

4. Execute a query

Use the execute Update() method of the Statement object to execute DDL(Data Definition Language) and SQL commands that update a table (INSERT, UPDATE,DELETE).

      Eg:statement. execute Update("INSERT INTO STUDENT VALUES('Babu G C',"+"'HDCA',9600.00'1002')");

Use the executeQuery(...)method of the Statement object to executive a SQL statement the data retrieved from  database.

Eg:ResultSet rs = statement.execteQuery("SELECT *FROM STUDESNT");

6.Close the connection

     Connection.close();

Using Prepared Statements

The Prepared Statement object contains not just an SQL statement, but an SQL statement that has been precompiled. This means that when the Prepared Statement is executed, the DBMS can just run the prepare Statement's SQL STATEMENT without having  to complete it first. The advantage of using prepared Statement is it can take parameters.

Creating a Prepared Statement Object

       prepared Statement preStmt;

String qry = "UPDATE STUDENT SET COURSE=? WHERE STUDNO=?"

preStmt = con.prepare Statement(qry);

Supplying Values for Prepared Statement parameters

You will need to supply values to be used in place of the question mark placeholders, if there are any, before you can execute a Prepared Statement object. You do this by calling one of the setter methods defined in the interface Prepared Statement. If the value you want to substitute for a question mark is a Java String, you call the method set String, and so on.

          PreStmt.setString(1, "HDCA");

           PreStmt.setInt(2, 1001);

After these values have been set for its two input parameters, Use the execute Update method to execute the Prepared Statement.