JDBC

JDBC:

• The JDBC ( Java Database Connectivity) API defines interfaces and classes for writing database applications in Java by making database connections. 
• Using JDBC you can connect to the database and execute any type of statements related relational database. 
• JDBC is a Java API for executing SQL statements and supports basic SQL functionality. 

JDBC Architecture:

http://instanceofjavaforus.blogspot.in/

• Java application calls the JDBC API. JDBC loads a driver which connects to the database.

Connectivity Steps to JDBC:

5 Steps to connect java Application with the database using JDBC.They are:

• Register the driver class
• Creating Connection
• Creating Statement
• Execting Queries
• Closing Connection

Register the driver class:

• The forName() of class is used to register the driver class.Using this class is used load the class dynamically.

try {

Class.forName(com.mysql.jdbc.Driver”); //Or any other driver

}

catch(Exception x){

System.out.println( “Unable to load the driver class!” );

}

Creating the Connection:

• DriverManager is the backbone of JDBC architecture. DriverManager class manages the JDBC drivers that are installed on the system. 
• Its getConnection() method of Driver Manager class is used to establish a connection to a database. It uses a username, password, and a jdbc url to establish a connection to 
• the database and returns a connection object.

try{

 Connection dbConnection=DriverManager.getConnection(url,”loginName”,”Password”)

}

catch( SQLException x ){

System.out.println( “Couldn’t get connection!” );

}

Creating Statement:

• Once a connection is established we can interact with the database. Connection interface defines methods for interacting with the database via the established connection. Statement 
• A statement object is used to send and execute SQL statements to a database.

       statement = dbConnection.createStatement();

Three kinds of Statements:

• Statement
• Prepared Statement
• Callable Statement

Statement:

• Execute simple sql queries without parameters.

         Statement createStatement().

Prepared Statement: 

• Execute precompiled sql queries with or without parameters.

        PreparedStatement prepareStatement(String sql).

Callable Statement: 

• Execute a call to a database stored procedure.

       CallableStatement prepareCall(String sql)

Executing Queries:

• Statement interface defines methods that are used to interact with database and execution of SQL statements.
• The Statement class has three methods:

• executeQuery()
• executeUpdate()
• execute(). 

executeQuery():

• For a SELECT statement, the method to use is executeQuery . 

executeUpdate():

• For statements that create or modify tables, the method to use is executeUpdate. 
• statements and are executed with the method executeUpdate. 

execute():

• execute() executes an SQL statement that is written as String object.

Connection Close():

• This method is used to close the connection.

          con.close();

Syntax:

public void close() throws SQLException.