JDBC: Steps to connect with Database


There are 5 steps to connect any java application with the database by using JDBC. They are as follows:

  1. Register the driver class
  2. Creating connection
  3. Creating statement
  4. Executing queries
  5. Closing connection

JDBC Steps for Connections

Register the driver class

The forName() method of Class class is used to register the driver class. This method is used to dynamically load the driver class.


public static void forName(String className)throws
Class.forName("oracle.jdbc.driver.OracleDriver");

Create the connection object

The getConnection() method of DriverManager class is used to establish connection with the database.


1) public static Connection getConnection(String url)throws SQLException
2) public static Connection getConnection(String url,String name,String password)
throws SQLException

Ex: Connect with Oracle

Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","system","password");

Create the Statement object

The createStatement() method of Connection interface is used to create statement. The object of statement is responsible to execute queries with the database.


public Statement createStatement()throws SQLException
Statement stmt=con.createStatement();

Execute the query

The executeQuery() method of Statement interface is used to execute queries to the database. This method returns the object of ResultSet that can be used to get all the records of a table.


public ResultSet executeQuery(String sql)throws SQLException
ResultSet rs=stmt.executeQuery("select * from emp");

while(rs.next()){
System.out.println(rs.getInt(1)+" "+rs.getString(2));
}

Close the connection object

By closing connection object statement and ResultSet will be closed automatically. The close() method of Connection interface is used to close the connection.


public void close()throws SQLException

 

See Also :

More on JDBC

Follow below links to know more on JDBC and solving JDBC issues :

JDBC Tutorial

JDBC Sample Code

JDBC Issues and Solutions

JDBC Interview Questions And Answers

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