Troubleshooting “Call to Undefined Function

MySQL Extension


If you are a PHP developer, it is likely that you have encountered the “Call to undefined function mysql_connect()” error at some point in your career. This error occurs when you attempt to use the deprecated MySQL extension in PHP 7.0 or later. If you are using PHP 5.x or earlier, you may have used the mysql_connect() function to connect to a MySQL database. However, this function has been removed in PHP 7.0 and later versions. In this blog post, we will discuss some of the solutions to this error.

Solution 1: Switch to MySQLi Extension

The MySQLi extension is an improved version of the MySQL extension, and it supports all the features of MySQL. If you want to continue using the MySQL database, you should switch to the MySQLi extension. The MySQLi extension offers both procedural call to undefined function mysql_connect() and object-oriented interfaces, and it is easy to use. To connect to the MySQL database using MySQLi, you can use the mysqli_connect() function. Here is an example of how to use mysqli_connect() function:

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);

// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
echo "Connected successfully";

Solution 2: Switch to PDO Extension

Another solution to this error is to switch to the PDO extension. PDO stands for PHP Data Objects, and it is a database abstraction layer that provides a consistent interface for accessing different databases. PDO supports a wide range of databases, including MySQL, PostgreSQL, SQLite, and Oracle. PDO is an object-oriented extension, and it provides a set of classes that you can use to connect to the database. Here is an example of how to use PDO to connect to a MySQL database:

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    echo "Connected successfully";
} catch(PDOException $e) {
    echo "Connection failed: " . $e->getMessage();

Solution 3: Use PHP Docker Image with MySQL Extension

If you have an application that requires the use of the deprecated MySQL extension, you can use a PHP Docker image that includes the MySQL extension. For example, the official PHP Docker image includes the MySQL extension, and you can use it to run your application. Here is an example of how to run a PHP Docker image with the MySQL extension:

docker run -d -p 80:80 --name my-php-app -v "$PWD":/var/www/html php:7.2-apache


The “Call to undefined function mysql_connect()” error can be frustrating for PHP developers. However, there are several solutions to this error. You can switch to the MySQLi extension, switch to the PDO extension, or use a PHP Docker image that includes the MySQL extension. By following these solutions, you can continue to use the MySQL database in your PHP applications.

It is important to note that the mysql_connect() function has been removed in PHP 7.0 and later versions. Therefore, if you are using PHP 7.0 or later, you should use a different method to connect to your MySQL database. It is also recommended to update your code to use prepared statements and parameterized queries to prevent SQL injection attacks.

I’m sorry, I realize that my previous response was a repetition of what was already stated in the document. Is there anything else you would like me to add or clarify regarding the “Call to Undefined Function mysql_connect()” error?

I see that you have already covered all the possible solutions to the “Call to Undefined Function mysql_connect()” error. Thank you for providing detailed information on how to resolve this issue.

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