Nando,

Thank you. I added b.EffDt to the SELECT and GROUP BY clauses and it
worked.

Bill



B> The error indicates that Max() can no longer be used in the having
clause.

not really. See below.

B> select b.CntId, Prd.Dsc, max(a.EffDt)
B> from Cnt a, Cnt b, Prd, SchCtl
B> where a.CntEntId = b.CntEntId
B> and a.PrdId = b.PrdId
B> and b.PrdId = Prd.PrdId
B> and a.CntEntId = 2
B> and Prd.PyrId = 8
B> and a.CntId = SchCtl.CntId
B> group by b.CntId, Prd.Dsc
B> having b.EffDt = max(a.EffDt) <--- gives error message below
B> order by Prd.Dsc

B> Error message: Invalid expression in the HAVING clause (neither an
aggregate
B> function nor a part of the GROUP BY clause)

B> I set the group by to look like this:

B> group by b.CntId, Prd.Dsc, max(a.EffDt)

B> and that didn't work either.

B> Any suggestions?

N> Yes. This query doesn't make sense and you should thank Firebird for
N> telling you. :-) The problem is that you can only include in the HAVING
N> clause columns that are also parte of the GROUP BY clause or aggregate
N> functions. b.EffDt doesn't satisfy the requirement.

N> I haven't got a clue what kind of result you expect, but I hope this
N> information will be useful to fix your query.

Ciao
--
Nando Dessena