connect to database using java

Connecting to a MySQL Database in Java

    

In java we have been provided with some classes and APIs with which we can make use of the database as we like.
Database plays as very important role in the programming because we have to store the values somewhere in the back- end.
So, we should know how we can manipulate the data in the database with the help of java,  instead of going to database for
a manipulation. We have many database provided like Oracle, MySQL etc. We are using MySQL for developing this application.

In this section, you will learn how to connect the MySQL database with the Java file. Firstly, we need to establish a
connection between MySQL and Java files with the help of MySQL driver .  Now we will make our  account in MySQL database
so that we can get connected to the database. After establishing a connection  we can access or retrieve data form MySQL
database. We are going to make a program on connecting to a MySQL database, after going through this program you will be
 able to establish a connection on your own PC.

Description of program:

This program establishes the connection between MySQL database and java files with the help of various types of APIs interfaces
and methods. If connection is established then it shows "Connected to the database" otherwise it will displays a message "Disconnected
from database".

Description of code:

Connection:
This is an interface in  java.sql package that specifies connection with specific database like: MySQL, Ms-Access, Oracle etc and
java files. The SQL statements are executed within the context of the Connection interface.
Class.forName(String driver):
This method is static. It attempts to load the class and returns class instance and takes string type value (driver) after that
 matches class with given string.

DriverManager:
It is a class of java.sql package that controls a set of JDBC drivers. Each driver has to be register with this class.

getConnection(String url, String userName, String password):
This method establishes a connection to specified database url. It takes three string types of arguments like:

    url: - Database url where stored or created your database
  userName: - User name of MySQL
  password: -Password of MySQL

con.close():
This method is used for disconnecting the connection. It frees all the resources occupied by the database.

printStackTrace():
The method is used to show error messages. If the connection is not established then exception is thrown and print the message.

import java.sql.*;

public class MysqlConnect{
  public static void main(String[] args) {
  System.out.println("MySQL Connect Example.");
  Connection conn = null;
  String url = "jdbc:mysql://localhost:3306/";
  String dbName = "jdbctutorial";
  String driver = "com.mysql.jdbc.Driver";
  String userName = "root";
  String password = "root";
  try {
  Class.forName(driver).newInstance();
  conn = DriverManager.getConnection(url+dbName,userName,password);
  System.out.println("Connected to the database");
  conn.close();
  System.out.println("Disconnected from database");
  } catch (Exception e) {
  e.printStackTrace();
  }
  }
}