java database connection example

Example 1: java connect to mysql

import java.sql.*;  
class MySqlConn{  
    public static void main(String args[]){  
        try{  
            Class.forName("com.mysql.cj.jdbc.Driver");  
            Connection conn = DriverManager.getConnection("jdbc:mysql://
            localhost:3306/databasename","username","password");  
            Statement stmt = conn.createStatement();  
            ResultSet rs = stmt.executeQuery("select * from emp");    
            con.close();  
        }catch(Exception ex){
            System.out.println(ex);
        }  
    }
}

Example 2: java sql connection example

import java.sql.*;

class MySQLConnection{

public static final String DBNAME = "name_of_the_database";  // Like "testDB"

/** JDBC driver name and database URL */
public static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";

/** Gives access to all Databases */
static final String ALL_DBS_URL = "jdbc:mysql://localhost/?allowPublicKeyRetrieval=true&autoReconnect=true&useSSL=false";

/** Gives access to a given DB */
static final String GIVEN_DB_URL = "jdbc:mysql://localhost/"+DBNAME+"?allowPublicKeyRetrieval=true&autoReconnect=true&useSSL=false";

// Below are the USERNAME and PASSWORD used in mysql
public static final String USER = "myUserName";
public static final String PASS = "myGoodPassWord";

/** A variable for connecting to MySQL Server */
public static Connection conn = null;

/** A variable for Preparing Statements */
public static PreparedStatement ps = null;

public static void main(String[] args) 
			throws ClassNotFoundException, SQLException {
		// Register JDBC driver
		Class.forName(JDBC_DRIVER);
		
		// Open a connection with MySQL server
		System.out.println("Connecting to all Databases path...");
		conn = DriverManager.getConnection(ALL_DBS_URL, USER, PASS);
		System.out.println("Connected to all Databases!");
		
		// Test if there is the db in MySQL Server
		// if not then create one
		System.out.println("Testing if "+DBNAME+" exists...");
		ps = conn.prepareStatement("CREATE DATABASE IF NOT EXISTS "+DBNAME+";");
		ps.executeUpdate();
		// Now db exists for sure!
		
		// Open a connection with given DB
		System.out.println("Connecting to "+DBNAME+" path...");
		conn = DriverManager.getConnection(GIVEN_DB_URL, USER, PASS);
		System.out.println("Connected to "+DBNAME+"!");
  		
  		// then you can do all sort of queries that you want to do
}
}