What potential issue could arise from using the mysql_connect function in PHP?

One potential issue that could arise from using the `mysql_connect` function in PHP is that it is deprecated as of PHP 5.5.0 and removed in PHP 7.0.0. This means that using `mysql_connect` can lead to compatibility issues and security vulnerabilities. To solve this problem, it is recommended to use the `mysqli_connect` or `PDO` extension for connecting to MySQL databases in PHP.

// Using mysqli_connect to establish a connection to a MySQL database
$servername = "localhost";
$username = "username";
$password = "password";
$database = "dbname";

$conn = mysqli_connect($servername, $username, $password, $database);

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