How to connect Database using JDBC?

Connect to the database.

• We can use JDBC API to handle database using Java program and can perform the following activities:

• 1. Register the Driver class

• The forName() method of Class is used to register the Driver class.
• This method is used to dynamically load the Driver class.
• Syntax:

public static void forName(String className)throws ClassNotFoundException

• Example:

//register code for Oracle database
Class.forName("oracle.jdbc.driver.OracleDriver");
//register code for MySQL database
Class.forName("com.mysql.jdbc.Driver");

Note: Since JDBC 4.0, no need to registering the driver.

• 2. Create connection
• The getConnection() method of DriverManager class is used to establish a connection with the database.
• Syntax:

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

• Example:

//mysql connection
Connection con=DriverManager.getConnection(
"jdbc:mysql://localhost:3306/sonoo","root","root");
//oracle connection
Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","system","password");

• 3. Create statement
• The createStatement() method of Connection interface is used to create a statement. The object of the statement is responsible to execute queries with the database.
• Syntax:

public Statement createStatement()throws SQLException

• Example:

Statement stmt=con.createStatement();

• 4. Execute queries
• 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.
• Syntax:

public ResultSet executeQuery(String sql)throws SQLException

• Example:

ResultSet rs=stmt.executeQuery("select * from emp");
while(rs.next()){
System.out.println(rs.getInt(1)+" "+rs.getString(2));
}

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

public void close()throws SQLException

• Example:

con.close();