Custom error handler for catching MySQL errors

mysql_error_catcher.php

<?php

function wp_set_error_handler() {
	if ( defined( 'E_DEPRECATED' ) )
			$errcontext = E_WARNING | E_DEPRECATED;
		else
			$errcontext = E_WARNING;

	set_error_handler( function( $errno, $errstr, $errfile ) {
		if ( 'wp-db.php' !== basename( $errfile ) ) {
			if ( preg_match( '/^(mysql_[a-zA-Z0-9_]+)/', $errstr, $matches ) ) {
				_doing_it_wrong( $matches[1], __('Please talk to the database using $wpdb' ), '3.7' );

				return apply_filters( 'wpdb_drivers_raw_mysql_call_trigger_error', true );
			}
		}

		return apply_filters( 'wp_error_handler', false, $errno, $errstr, $errfile );
	}, $errcontext );
}

wp_set_error_handler();