HAVING clause is a case statement??

i have wrote a query which compares two tables, returning anywhere the qty is not the same in each table:

(simple ex)

Select order_no
from table1
inner join table2
on table1.order_no = table2.order_no
group by order_no
having table1.Qty<> table2.Qty

BUT... I need to add a table3, where there maybe (or may not be enters - thus a left join). If there is an entry in table3 then use qty in table3 and not table1... so having becomes:

CASE WHEN table1.Qty<> table3.Qty
THEN table3.Qty<> table2.Qty
ELSE table1.Qty<> table2.Qty END

but how do i actually write this?perhaps if you would care to explain what you're doing?

are you comparing individual Qty values, or the SUMs?

because the HAVING clause may refer only to columns in the GROUP BY or to aggregate functions|||perhaps if you would care to explain what you're doing?

are you comparing individual Qty values, or the SUMs?

because the HAVING clause may refer only to columns in the GROUP BY or to aggregate functions

Sorry I am trying to compare Sum(qty) for each product in an order (product maybe in the order more than 1ce) I am trying to retrieve any product lines where Sum qties in table1 and table2 are not the same.

However, if stock was not found, then an allocated qty is recorded in table 3...so in this case I want to compare qtyies in table3 and table2
?|||select t1.order_no
, t1.sumqty
, t2.order_no
, t2.sumqty
from (
select order_no
, sum(qty) as sumqty
from table1
group
by order_no
) as t1
full outer
join (
select order_no
, sum(qty) as sumqty
from table2
group
by order_no
) as t2
on t2.order_no = t1.order_no
and t2.sumqty <> t1.sumqtythat's the general strategy -- do your sums in derived tables

for table 3, you're on your own :)