Connect to MySQL, PostgreSQL using JDBC

Now I will show you how to connect to MySQL and PostgreSQL database using JDBC connector.
We need connector.
Download MySQL connector.
Download PostgreSQL connector.

In Eclipse:
Right click on your Java project -> Buil Path -> Configure Build Path -> Java Build Path and add your jar

1. Short example (for MySQL):

Connection con = null;
Statement stmt;
ResultSet rs;

Class.forName( "com.mysql.jdbc.Driver" ).newInstance();
con = DriverManager.getConnection( "jdbc:mysql://hostname:port/dbname","username", "password" );
stmt = con.createStatement();

con.close();
stmt.close();
rs.close();

2. Full example:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBexample
{
 String dbLogin, dbPswd, dbUrl;
 
 Connection con = null;
 Statement stmt;
 ResultSet rs;
 
 /* There are two database systems:
  * - mysql
  * - pg */
 public DBexample( String databaseSystem )
 {
  if( databaseSystem.equals( "mysql" ) )
  {
   this.dbLogin = "root";
   this.dbPswd = "password";
   this.dbUrl = "jdbc:mysql://localhost:3306/dbname";
   
   try
   {
    Class.forName( "com.mysql.jdbc.Driver" ).newInstance();
    con = DriverManager.getConnection( this.dbUrl, this.dbLogin, this.dbPswd );
    stmt = con.createStatement();
   }
   catch (Exception e) 
   {
    System.out.println( "There is no connector available." );
    return;
   }  
   
   System.out.println( "Connector registered" );
   
  }
  else if( databaseSystem.equals( "pg" ) )
  {
   this.dbLogin = "root";
   this.dbPswd = "password";
   this.dbUrl = "jdbc:postgresql://localhost:5432/dbname";
   
   try
   {
    Class.forName( "org.postgresql.Driver" );
    con = DriverManager.getConnection( this.dbUrl, this.dbLogin, this.dbPswd );
    stmt = con.createStatement();
   }
   catch (Exception e)
   {
    System.out.println( "There is no connector available." );
    return;
   }
   
   System.out.println( "Connector registered" );
  }  
 }
 
 /* Execute sql: update, insert, delete... */
 public void executeUpdate(String aQuery) throws SQLException
 {
  stmt.executeUpdate(aQuery);
 }
 
 /* Execute sql: select... and get result */
 public ResultSet executeSelect( String aQuery )
 {
  try 
  {
   rs = stmt.executeQuery(aQuery);
  } 
  catch (SQLException e) 
  {  
   e.printStackTrace();
  }    
  return rs;
 }
 
 public void closeConnection() throws SQLException
 {
  con.close();
  stmt.close();
  rs.close();
 }
 
 /* Test */
 public static void main(String[] argv) throws SQLException 
 {
  ResultSet rs;
  
  /* Connect to MySQL and get all cars */
  DBexample dbMySQL = new DBexample("mysql");
  rs = dbMySQL.executeSelect("SELECT * FROM cars");  
  
  try 
  {
   while( rs.next() )
   {
    String carModel = rs.getString( "model" );
    System.out.println( carModel );   
   }
  } 
  catch (SQLException e) 
  {  
   e.printStackTrace();
  }
  /* close connection */
  dbMySQL.closeConnection();
  
  /* *********************************************************************** */
  
  /* Connect to PostgreSQL and get all users */
  DBexample dbPg = new DBexample("pg");
  rs = dbPg.executeSelect("SELECT * FROM users");
  
  try 
  {
   while( rs.next() )
   {
    String userName = rs.getString( "userName" );
    System.out.println( userName );   
   }
  } 
  catch (SQLException e) 
  {  
   e.printStackTrace();
  }
  /* close connection */
  dbPg.closeConnection();
 }
}

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