MySQL query nested in an if statement - PHP

Can a MySQL query string be nested inside an if statement as shown below?

if (mysql_query($queryString)) {
    return true;
}
else {
    return $error;
}

If this is not possible, what is the best way to make sure that the query has been executed by the query that is inside the if statement?

(I know that MySQL has been depreciated now, but to change it across the site that I am building would be far to difficult and long-winded)