Question

I have a query like this:

SELECT TPCombined.Title, 
GROUP_CONCAT(DISTINCT CONCAT(a.LastName, ', ', a.FirstName) SEPARATOR '<br />') as Author 
FROM ((SELECT b.Title FROM BookList b) UNION (SELECT s.Title FROM Studios s)) 
AS TPCombined 
LEFT OUTER JOIN (AuthorLinks al JOIN Authors a ON al.AuthorStem = a.AuthorStem) 
ON TPCombined.BookStem = al.BookStem 
WHERE Author LIKE '%Smith%' GROUP BY BookStem; 

This query doesn’t work:

Unknown column ‘Author’ in ‘where clause’

This would work with HAVING instead of WHERE. But I really need to use Where. Could you please confirm if this is really impossible? Or maybe I can fix the query somehow to make it work with Where?

Answer 1

WHERE clauses are applied at the row level. You’ve aliased an aggregate function as Author, which means its results won’t be available at the row level – only when the query is complete and ready to go to the client. You’d need to use a HAVING filter instead, which is applied just before sending to client.