How to use PDO to DELETE data from MySQL using PHP

You need to delete data safely from a web page and your MySQL table in your database

You need to sanitize that data from user input and protect against SQL injections.

The following simple example will show you how to accomplish that.

These are the ingredients you will need:

  1. A MySQL database
  2. A table to store the data in the above database
  3. The credentials to above (the host location, username and password)
  4. Which you can use to create a connection in your PHP page
  5. A list of records displaying your data
  6. A way to select and delete a record
  7. Safely delete the data

What if you don’t have all of the above set-up?

Don’t worry at the end will be a link to example PHP source code along with the SQL statements to create the database and table.

PHP PDO (PHP Data Objects) makes it very easy to DELETE data from your table.

First, to connect to the database with PDO is very simple:

$dbh = new PDO('mysql:host=localhost;dbname='. $db_name, $db_username, $db_password);

The above line creates a connection and stores it in the $dbh variable as an object

That variable can then be used to delete the data using a DELETE statement:

$stmt = $dbh->prepare('DELETE FROM makes WHERE id = :id');

This prepares a statement which we can then bind the id parameter safely too, protecting against SQL injections.

We use PHP’s filer_input() function to santize the data and make sure it’s an integer. The GET parameter comes from the query string in the URL of the delete.php page:

$id = filter_input(INPUT_GET, 'id', FILTER_SANITIZE_NUMBER_INT);

The $id variable can then be bound to the prepared statement:

$stmt->bindParam(':id', $id, PDO::PARAM_INT);

Then the statement is executed to run the prepared SQL statement, resulting in the record being deleted from the MySQL database table:

$stmt->execute()

These are the key lines to connect to the database. Sanitize the query string variable and DELETE the record in the database.

Of course the above doesn’t show the HTML need to make the form and input field.

You can find that here, on github as a simple PHP PDO CRUD Demo. Please download / fork the code and try it out.

The demo is a simple CRUD example of using PHP, PDO and MySQL to display a list of car makes

This post is a part of a series, you can read more about viewing the data with PDO here. Which generates the delete link to delete.php

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