获取详细信息与php匹配的行的ID

I have a php file which is gathering the username and password and checking it against the database, if it matches then the user logs on. Is it possible to get the ID of this row and store this in a variable ready for a session ?

I'm currently using this statement.

$query = mysql_query("select * from users where password='$password' AND    username='$username'", $connection);

Thanks all

Yes, there is a way:

$query = mysql_query("select * from users where password='$password' AND    username='$username'", $connection);
$row = mysql_fetch_array($query);
$id = $row['user_id']; //change user_id to the column name

But don't use mysql_*, use mysqli_* instead.