This tutorial provides an example on how to delete records from a table using JDBC application. Before executing following example, make sure you have the following in place:
To execute the following example you can replace username and password with your actual user name and password.
Your MySQL or whatever database you are using is up and running.
There are following steps required to create a new Database using JDBC application:
Import the packages: Requires that you include the packages containing the JDBC classes needed for database programming. Most often, using import java.sql.* will suffice.
Register the JDBC driver: Requires that you initialize a driver so you can open a communications channel with the database.
Open a connection: Requires using the DriverManager.getConnection() method to create a Connection object, which represents a physical connection with a database server.
Execute a query: Requires using an object of type Statement for building and submitting an SQL statement to delete records from a table. This Query makes use of WHERE clause to delete conditional records.
Clean up the environment: Requires explicitly closing all database resources versus relying on the JVM's garbage collection.
Copy and paste below code in example.java, compile and run:
//STEP 1. Import required packages import java.sql.*; public class example { // 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{ //STEP 2: Register JDBC driver Class.forName("com.mysql.jdbc.Driver"); //STEP 3: Open a connection System.out.println("Connecting to a selected database..."); conn = DriverManager.getConnection(DB_URL, USER, PASS); System.out.println("Connected database successfully..."); //STEP 4: Execute a 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 the records // to see the remaining records sql = "SELECT id, first, last, age FROM Registration"; ResultSet rs = stmt.executeQuery(sql); while(rs.next()){ //Retrieve by column name int id = rs.getInt("id"); int age = rs.getInt("age"); String first = rs.getString("first"); String last = rs.getString("last"); //Display values 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){ //Handle errors for JDBC se.printStackTrace(); }catch(Exception e){ //Handle errors for Class.forName e.printStackTrace(); }finally{ //finally block used to close resources try{ if(stmt!=null) conn.close(); }catch(SQLException se){ }// do nothing try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); }//end finally try }//end try System.out.println("Have A Nice Day"); }//end main }//end example
Now compile above example:
C:\>javac example.java C:\>
C:\>java example Connecting to a selected database... Connected database successfully... Creating statement... ID: 100, Age: 24, First: Sophia, Last: Lomela ID: 102, Age: 24, First: Guru, Last: Morkel ID: 103, Age: 22, First: Simone, Last: Washer Have A Nice Day C:\>
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