How to DELETE data from a MySQL database in WordPress

A guide on how to use Prepared Statements in WordPress to delete data from a MySQL database safely and effectively.

In this article, you will learn how to use Prepared Statements in WordPress to execute a DELETE statement, allowing you to remove records from tables in the WordPress database using multiple parameters.

global $wpdb;

// DELETE statement with Prepared Statement
$delete_query = $wpdb->prepare("DELETE FROM wp_students WHERE id = %d AND name = %s", $id, $name);

// Execute the DELETE statement
$result = $wpdb->query($delete_query);

// Check the number of records deleted
if ($result) {
    echo "$result record(s) deleted.";
} else {
    echo "No records were deleted.";
}

Detailed explanation:

1. global $wpdb;: Uses the global $wpdb object in WordPress to interact with the database.
2. $delete_query = $wpdb->prepare(...): Creates the DELETE statement with parameters, where %d and %s represent integer and string data types, respectively.
3. $result = $wpdb->query($delete_query);: Executes the DELETE statement and stores the result (number of records deleted).
4. if ($result) {...}: Checks if any records were deleted and prints the appropriate message.

System Requirements:

• A running WordPress installation (latest version recommended).
• Access to the MySQL database used by WordPress.

How to install the libraries needed to run the PHP code above:

No additional libraries are needed, as $wpdb is a built-in object in WordPress.

Tips:

• Always back up your database before performing DELETE operations to prevent loss of important data.
• Carefully check input parameters to ensure you do not accidentally delete unintended data.
• Use Prepared Statements to protect against SQL injection attacks.