A simple Java application showing how to query a table in a database i.e performing a delete 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 "customer". Run the create query stated below -
CREATE TABLE customer ( 'First Name' varchar(30) , 'Last Name' varchar(30) , 'E-Mail' varchar(45) , 'City' varchar(30) , 'password' varchar(30) NOT NULL, PRIMARY KEY ('password') )
4. Populate the table user with some data (of your own), if not run the four insert queries stated below -
insert into customer () values ('Jonty','Magic','jonty@magic.com','Pune','123456'); insert into customer () values ('Java','Sun','java@sun.com','New York','456'); insert into customer () values ('Jesse','lool','jesse@lool.com','Jamaica','23456'); insert into customer () values ('Cameroon','Black','cameroon@black.com','Sydney','34');
5. Create a Java Class. It will perform necessary insert query. 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.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class DeleteJdbcQuery { Connection connection = null; ResultSet resultSet = null; Statement statement = null; static String query = null; String url = null; String username = null; String password = null; public static void main(String[] args) { DeleteJdbcQuery djq = new DeleteJdbcQuery(); djq.createConnection(); query = "delete from customer where First_Name='Jonty';"; djq.executeQuery(query); query = "delete from customer where First_Name='Java';"; djq.executeQuery(query); djq.release(); } private void release() { try { statement.close(); connection.close(); } catch (SQLException se) { se.printStackTrace(); } } 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(String query) { try { statement = connection.createStatement(); statement.execute(query); } catch (SQLException e) { e.printStackTrace(); } } }
Output after Insert query -
Output after Delete query -