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Java & MySQL - Delete Records
  • 时间:2024-12-27

Java & MySQL - Delete Records Example


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This chapter provides an example on how to delete records from a table using JDBC apppcation. Before executing following example, make sure you have the following in place −

    To execute the following example you can replace the username and password with your actual user name and password.

    Your MySQL database you are using is up and running.

Required Steps

The following steps are required to create a new Database using JDBC apppcation −

    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 initiapze 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 the WHERE clause to delete conditional records.

    Clean up the environment − try with resources automatically closes the resources.

Sample Code

Copy and paste the following example in TestApppcation.java, compile and run as follows −


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

pubpc class TestApppcation {
   static final String DB_URL = "jdbc:mysql://localhost/TUTORIALSPOINT";
   static final String USER = "guest";
   static final String PASS = "guest123";
   static final String QUERY = "SELECT id, first, last, age FROM Registration";

   pubpc static void main(String[] args) {
      // Open a connection
      try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
         Statement stmt = conn.createStatement();
      ) {		      
         String sql = "DELETE FROM Registration " +
            "WHERE id = 101";
         stmt.executeUpdate(sql);
         ResultSet rs = stmt.executeQuery(QUERY);
         while(rs.next()){
            //Display values
            System.out.print("ID: " + rs.getInt("id"));
            System.out.print(", Age: " + rs.getInt("age"));
            System.out.print(", First: " + rs.getString("first"));
            System.out.println(", Last: " + rs.getString("last"));
         }
         rs.close();
      } catch (SQLException e) {
         e.printStackTrace();
      } 
   }
}

Now let us compile the above example as follows −


C:>javac TestApppcation.java
C:>

When you run TestApppcation, it produces the following result −


C:>java TestApppcation
ID: 100, Age: 30, First: Zara, Last: Ap
ID: 102, Age: 30, First: Zaid, Last: Khan
ID: 103, Age: 28, First: Sumit, Last: Mittal
C:>
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