Deleting Data using JDBC

Using Statement:

• Statement is suitable for executing simple SQL queries without parameters.

Steps to Execute a DELETE Query Using Statement:

1. Establish a Connection: Establish a connection to the database.

2. Create a Statement: Create a Statement object using the connection.

3. Execute Query: Execute the SQL DELETE query using the Statement.

Example Code using Statement (Java):

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

public class StatementDeleteExample {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "username";
        String password = "password";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
             Statement statement = connection.createStatement()) {

            String sqlQuery = "DELETE FROM users WHERE id = 1";
            int rowsAffected = statement.executeUpdate(sqlQuery);

            if (rowsAffected > 0) {
                System.out.println("Data deleted successfully!");
            } else {
                System.out.println("Failed to delete data.");
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Using PreparedStatement:

• PreparedStatement is used for executing parameterized SQL queries.

Steps to Execute a DELETE Query Using PreparedStatement:

1. Establish a Connection: Establish a connection to the database.

2. Create a PreparedStatement: Create a PreparedStatement object with the parameterized query using the connection.

3. Set Parameters: Set the parameter values using setter methods of the PreparedStatement.

4. Execute Query: Execute the PreparedStatement.

Example Code using PreparedStatement (Java):

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

public class PreparedStatementDeleteExample {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "username";
        String password = "password";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password)) {
            String sqlQuery = "DELETE FROM users WHERE id = ?";
            int userId = 2;

            try (PreparedStatement preparedStatement = connection.prepareStatement(sqlQuery)) {
                preparedStatement.setInt(1, userId);

                int rowsAffected = preparedStatement.executeUpdate();

                if (rowsAffected > 0) {
                    System.out.println("Data deleted successfully!");
                } else {
                    System.out.println("Failed to delete data.");
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Explanation:

• StatementDeleteExample: Uses Statement to delete the user with ID 1 from the users table.

• PreparedStatementDeleteExample: Uses PreparedStatement to delete the user with a specific ID from the users table. Parameters (?) are used for values that will be replaced during execution, providing protection against SQL Injection.