Java and MySQL – Updating Data

In order to update data in a MySQL database, the SQL ‘Update’ statement needs to be used. The following example updates the record in the ‘person’ table that was added in the example for inserting data.

Updating data follows the same pattern as inserting data. Firstly, a connection to the database is established, then the query parameters are defined as variables, which are bound in to the following SQL statement. One of the parameters is for an ‘id’, so that only the specified record is updated, in this case, the record with an ‘id’ of five. The other parameters are for updating the ‘lastname’ and ‘title’ fields against the record. The SQL statement is then executed and a confirmation message is displayed. The execution of the SQL statement is wrapped in a ‘try-catch’ block to catch any errors that may arise.

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

public class DemoMySQL {

    public static void main(String[] args) {

        // Connection variable.
        Connection connect = null;

        try {

            // Connect to database.
            connect = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/Demo?useSSL=false",
                    "DemoUN", "DemoPW");

        } catch (SQLException e) {

            // Confirm unsuccessful connection and stop program execution.
            System.out.println("Database connection unsuccessful.");
            System.exit(0);

        }

        // Query parameters.
        String lastname = "Bloggs";
        String title = "Mrs";
        Integer id = 5;

        // SQL to update data in the person table.
        String sqlUpdate =
                "UPDATE person " +
                "SET lastname = ?, " +
                "    title = ? " +
                "WHERE id = ?";

        try {

            // Create statement and bind the parameters.
            PreparedStatement statement = connect.prepareStatement(sqlUpdate);
            statement.setString(1, lastname);
            statement.setString(2, title);
            statement.setInt(3, id);

            // Execute query.
            statement.executeUpdate();

            // Confirm successful updating of person information.
            System.out.println("Person information updated successfully.");

            // Close the statement and database connection.
            statement.close();
            connect.close();

        } catch (SQLException e) {

            // Confirm error updating person information and quit.
            System.out.println("Error updating person information.");
            System.exit(0);

        }

    }

}

The contents of the ‘person’ table now looks as follows.

id firstname lastname title dob
1 Bob Smith Mr 1980-01-20
2 George Jones Mr 1997-12-15
3 Fred Bloggs Mr 1975-05-07
4 Alan White Mr 1989-03-20
5 Fiona Bloggs Mrs 1985-05-19