MySQL Database Connection in Java

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.

Code of program:

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();

}

}

}

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Delete Data Records Using JSP, My Sql

deleteRecords.jsp

<%@ page language = "java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ page import = "java.sql.*"%>

<%! boolean success = false; %>

<%

int delID = Integer.parseInt(request.getParameter("deleteID"));

//String sql = "DELETE * FROM EMP_DETAIL WHERE ID = '"+delID+"'";

String sql = "DELETE FROM EMP_DETAIL WHERE ID = ?";

Connection con = null;

PreparedStatement psmt = null;

String url = "jdbc:mysql://localhost:3306/test_db";

String driver = "com.mysql.jdbc.Driver";

String userName = "root";

String password = "";

Class.forName(driver).newInstance();

con = DriverManager.getConnection(url, userName, password);

psmt = con.prepareStatement(sql);

psmt.setInt(1, delID);

int nRows = psmt.executeUpdate();

if(nRows == 0){

success = false;

}

else{

success = true;

}

psmt.close();

con.close();

%>

<%

if(success == true){

%>

One record deleted

View Records

<%

}

else{

%>

Can not delete record now. Please try later...

<%

}

%>

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Update Data Using JSP MySql

updateRecords.jsp

<%@ page language = "java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ page import = "java.sql.*"%>

<%@page import="java.util.*"%>

<%! boolean success = false; %>

<%

int id = Integer.parseInt(request.getParameter("tid"));

int eid = Integer.parseInt(request.getParameter("employeeID"));

String empName = request.getParameter("employeeName");

String sql= "UPDATE EMP_DETAIL SET emp_id = '"+eid+"', emp_name = '"+empName+"' WHERE id = '" +id+ "'";

Connection con = null;

PreparedStatement psmt = null;

String url = "jdbc:mysql://localhost:3306/test_db";

String driver = "com.mysql.jdbc.Driver";

String userName = "root";

String password = "";

Class.forName(driver).newInstance();

con = DriverManager.getConnection(url,userName,password);

psmt = con.prepareStatement(sql);

//psmt.setInt(2, eid);

//psmt.setString(3, empName);

int nRows = psmt.executeUpdate();

if(nRows == 0){

success = false;

}

else{

success = true;

}

psmt.close(); con.close();

%>

<%

if(success = true){

%>

Record updated

View Records

<%

}

else {

%>

Error - can not be updated

View Records

<%

}

%>

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Edit Records Using JSP MySql

editRecords.jsp

<%@ page language = "java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ page import = "java.sql.*"%>

<%@page import="java.util.*"%>

<%

int emp_id = Integer.parseInt(request.getParameter("editID"));

//String sql = "SELECT * FROM EMP_DETAIL WHERE ID= ? ";

Connection con = null;

PreparedStatement psmt = null;

String driver = "com.mysql.jdbc.Driver";

String url = "jdbc:mysql://localhost:3306/test_db";

String userName = "root";

String password = "";

ResultSet rs = null;

try {

Class.forName(driver).newInstance();

con = DriverManager.getConnection(url, userName, password);

String sql = "SELECT * FROM EMP_DETAIL WHERE ID='"+emp_id+"'";

psmt = con.prepareStatement(sql);

rs = psmt.executeQuery();

while(rs.next()){

%>

<%

}

}

catch(Exception e){

out.println("Error: " +e);

}

con.close();

psmt.close();

%>

>

Employee ID: >

Employee Name:

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Retrieve Data Using JSP MySQL

viewRecords.jsp

<%@ page language = "java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ page import = "java.sql.*"%>

<%

Connection con = null;

Statement stmt = null;

ResultSet rs = null;

String url = "jdbc:mysql://localhost/test_db";

String driver = "com.mysql.jdbc.Driver";

String userName = "root";

String password = "";

%>

<%

Class.forName(driver).newInstance();

con = DriverManager.getConnection(url, userName, password);

String sql = "SELECT * FROM EMP_DETAIL ORDER BY EMP_ID ASC";

stmt = con.createStatement();

rs = stmt.executeQuery(sql);

while(rs.next()){

//out.println(rs.getInt(1) +" : "+rs.getString(2) +"
");

int tID = rs.getInt(1);

int empID = rs.getInt(2);

String empName = rs.getString(3);

//out.print(" | ");

//out.println(rs.getString(2));

%>

<%

}

con.close();

//out.println("Data inserted");

%>

<%=empID%>

<%=empName%>

Edit

Delete

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Insert Record Using JSP MYSQL

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ page import = "java.sql.*"%>

<%

int emp_id = Integer.parseInt(request.getParameter("employeeID"));

String str2 = request.getParameter("employeeName");

String str_email = request.getParameter("employeeEmail");

Connection con = null;

PreparedStatement psmt = null;

String url = "jdbc:mysql://localhost:3306/test_db";

String driver = "com.mysql.jdbc.Driver";

//String dbName = "test_db";

String userName = "root";

String password = "";

try {

Class.forName(driver).newInstance();

con = DriverManager.getConnection(url, userName, password);

//con = DriverManager.getConnection(url+dbName, userName, password);

String sql = "INSERT INTO EMP_DETAIL(emp_id, emp_name, emp_email) VALUES (?, ?, ?)";

psmt = con.prepareStatement(sql);

psmt.setInt(1, emp_id);

psmt.setString(2, str2);

psmt.setString(3, str_email);

psmt.executeUpdate();

out.println("Thank you: Record inserted.");

}

catch (Exception e){

out.println("Error: "+e);

}

finally {

psmt.close();

con.close();

}

%>

View Record

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Create ID

createId.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

Employee ID:

Employee Name:

Employee Email ID:

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