function dbQuery($query, $identifier=''){ // $identifier for better debugging
GLOBAL $debugMode;
    $result=mysql_query($query);
    if (!$result) {
        $message = 'Invalid query $identifier: ' . mysql_error() . "<br />\n";
        if($debugMode) $message .= 'Whole query: ' . $query;
        die($message);
    }
}

function dbConnect($user, $pass, $db=FALSE, $host='localhost'){
    $link=mysql_connect($host,$user,$pass) or die('Could not connect to database: '.mysql_error());
    if(!empty($db)) mysql_select_db($db) or die("Could not select the database $db: ".mysql_error());
    return $link;
}

function strSafe($str, $char="'"){
	return str_replace($char, '\'.$char, $str);
}

functions instead of mysql_query and mysql_connect for error checking with debug mode and function strSafe for stopping sql inje

PHP