JDBC Delete Record

This chapter provides examples on how to use JDBC applications to delete records from a table. Before executing the following example, please ensure that you have the following conditions:

• To execute the following example, you can copyUsernameAndPasswordReplace with actual username and password.

• Your MySQL or any database you are using has been started and is running.

Necessary Steps

To create a new database using a JDBC application, you need to perform the following steps-

• Import Package:It requires you to include the package that contains the JDBC classes required for database programming. Typically, using import java.sql.* That's enough.

• Register JDBC Driver: It requires you to initialize the driver so that you can open a communication channel with the database.

• Establish connection:It is necessary to use　DriverManager.getConnection() A method to create a Connection object that represents a physical connection to the database server.

• Execute the query:It is necessary to use an object of the Statement type to construct and submit SQL statements to delete records from the table. This query usesWHERESub-clause to delete condition records.

• Clean up the environment: It is necessary to explicitly close all database resources instead of relying on JVM garbage collection.

Sample Code

Copy and paste the following example into JDBCExample.java, compile and run as follows-

//Step1.Import the required packages
import java.sql.*;
public class JDBCExample {
　　　//　JDBC Driver Name and Database URL
　　　static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";　　
　　　static final String DB_URL = "jdbc:mysql://localhost/STUDENTS";
　　　//　　Database Credentials
　　　static final String USER = "username";
　　　static final String PASS = "password";
　　　
　　　public static void main(String[] args) {
　　　Connection conn = null;
　　　Statement stmt = null;
　　　try{
　　　　　　//Step2: Register JDBC driver
　　　　　　Class.forName("com.mysql.jdbc.Driver");
　　　　　　//Step3: Establish connection
　　　　　　System.out.println("Connecting to a selected database...");
　　　　　　conn = DriverManager.getConnection(DB_URL, USER, PASS);
　　　　　　System.out.println("Connected database successfully...");
　　　　　　
　　　　　　//Step4: Execute query
　　　　　　System.out.println("Creating statement...");
　　　　　　stmt = conn.createStatement();
　　　　　　String sql = "DELETE FROM Registration "　+
　　　　　　　　　　　　　　　　　　　"WHERE id = "　101";
　　　　　　stmt.executeUpdate(sql);
　　　　　　//　Now you can extract all records
　　　　　　//　View remaining records
　　　　　　sql = "SELECT id, first, last, age FROM Registration";
　　　　　　ResultSet rs = stmt.executeQuery(sql);
　　　　　　while(rs.next()){
　　　　　　　　　//Search by column name
　　　　　　　　　int id = rs.getInt("id");
　　　　　　　　　int age = rs.getInt("age");
　　　　　　　　　String first = rs.getString("first");
　　　　　　　　　String last = rs.getString("last");
　　　　　　　　　//Display value
　　　　　　　　　System.out.print("ID: ",　+　id);
　　　　　　　　　System.out.print(", Age: ",　+　age);
　　　　　　　　　System.out.print(", First: ",　+　first);
　　　　　　　　　System.out.println(", Last: ",　+　last);
　　　　　　}
　　　　　　rs.close();
　　　}catch(SQLException se){
　　　　　　//Handling JDBC error
　　　　　　se.printStackTrace();
　　　}catch(Exception e){
　　　　　　//Handling Class.forName error
　　　　　　e.printStackTrace();
　　　}finally{
　　　　　　//For closing resources
　　　　　　try{
　　　　　　　　　if(stmt!=null)
　　　　　　　　　　　　conn.close();
　　　　　　}catch(SQLException se){
　　　　　　}//　Nothing to do
　　　　　　try{
　　　　　　　　　if(conn!=null)
　　　　　　　　　　　　conn.close();
　　　　　　}catch(SQLException se){
　　　　　　　　　se.printStackTrace();
　　　　　　}
　　　}
　　　System.out.println("Goodbye!");
}//End of main
}//End of JDBCExample

Now, let's compile the above example as follows:

C:\>javac JDBCExample.java
C:\>

RuntimeJDBCExampleIt will produce the following result-

C:\>java JDBCExample
Connecting to a selected database...
Connected database successfully...
Creating statement...
ID:　100, Age:　30, First: Zara, Last: Ali
ID:　102, Age:　30, First: Zaid, Last: Khan
ID:　103, Age:　28, First: Sumit, Last: Mittal
Goodbye!
C:\>