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How to perform select sql query in a Java application using JDBC ?



A simple Java application showing how to query a table in a database i.e performing a select query using JDBC

Steps for querying a Database using JDBC -

1. Download the driver jar from Internet and place it in classpath of your Java application. Here I am using MySql as Database so I have downloaded the jar with name as : "mysql-connector-java-5.1.20-bin.jar"

2. Create a Database (am using MySql as backend) name as "javaee".

3. Create a table in "javaee" database as "user". Run the create query stated below -

CREATE TABLE user (
  'First Name' varchar(30) ,
  'Last Name' varchar(30) ,
  'E-Mail' varchar(45) ,
  'password' varchar(30) NOT NULL,
  PRIMARY KEY ('password')
) 




4. Populate the table user with some data (of your own), if not run the three insert queries stated below -

INSERT INTO user () VALUES ( 'Jonty','Magic','jonty@magic.com','123456');

INSERT INTO user () VALUES ( 'JSP','Servlets','jsp@servlets.com','123');

INSERT INTO user () VALUES ( 'java','sun','java@sun.com','12');



5. Create a Java Class. It will perform necessary select query and output it to browser. The code for Java class is shown below -


package com.hubberspot.jdbc;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;


public class SelectJdbcQuery {

 Connection connection = null;
 ResultSet resultSet = null;
 PreparedStatement preparedStatement = null;
 String query = null;
 String url = null;
 String username = null;
 String password = null;

 public static void main(String[] args) {

  SelectJdbcQuery sjq = new SelectJdbcQuery();
  sjq.createConnection();
  sjq.executeQuery();

 }

 private void createConnection() {

  url = "jdbc:mysql://localhost:3306/javaee";
  username = "root"; 
  password = "root"; 
  try {
   Class.forName("com.mysql.jdbc.Driver").newInstance();

   connection = DriverManager.getConnection(url, username , password);
  }
  catch (Exception e) {

   e.printStackTrace();
  }


 }

 private void executeQuery() {

  query = "select * from User";
  try {
   preparedStatement = connection.prepareStatement(query);
   resultSet = preparedStatement.executeQuery();

   System.out.println("The Select query has following results : ");

   System.out.println("\n First Name\t Last Name\t Email");

   int i = 0;
   while(resultSet.next()) {

    System.out.print(" "+resultSet.getString(1) + "    \t");
    System.out.print(" "+resultSet.getString(2) + "    \t");
    System.out.println(" "+resultSet.getString(3) + "   \t");
    i++;

   }


  }
  catch (SQLException e) {

   e.printStackTrace();
  }
  finally {
   try {
    resultSet.close();
    preparedStatement.close();
    connection.close();

   }
   catch (SQLException e) {

    e.printStackTrace();
   } 
  }

 }

}



Output of the program :



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