The derived table is created first, right? In other words, we need to select everything from the original table and then would be able to apply conditions.

Thanks.

>You can use result of the query as derived table
>

>SELECT * FROM ( ;
>	SELECT Id, Forename, Compname, SUM(OrdTotal) TotOrd ;
>		FROM clients ;
>			LEFT JOIN Prsndetl ON Clients.Id = PrsnDetl.ClientId ;
>			LEFT JOIN Orders ON Clients.Id = Orders.ClientId ;
>		GROUP BY Clients.Id, Clients.Compname, PrsnDetl.Forename ) dt1 ;
>  WHERE '01' $ CompName ;
>			OR 'hr' $ LOWER(Forename) ;
>			OR TotOrd = 300
>

>for another wrapping query.