What are the potential pitfalls when upgrading from PHP 5.6 to PHP 7.0, especially in relation to database scripts?

When upgrading from PHP 5.6 to PHP 7.0, one potential pitfall in relation to database scripts is the use of deprecated functions or features that are no longer supported in PHP 7.0. To solve this issue, you should update your database scripts to use the newer, supported functions and features in PHP 7.0.

// Before upgrading from PHP 5.6 to PHP 7.0
// Using deprecated mysql_connect function
$conn = mysql_connect("localhost", "username", "password");

// After upgrading to PHP 7.0
// Update to use mysqli_connect function
$conn = mysqli_connect("localhost", "username", "password");