In the last episode (Jun 15), Edward Kay said:
> I have a table of addresses. Each address is associated with a primary
> entity and a primary entity can have n different addresses. For each primary
> entity, one address is marked as the main address.
>
> I need a query to return all addresses that are the only address associated
> with the primary entity but aren't marked as the main address.
>
> At the moment, I have this and it works:
>
> select * from contact_address
> group by primary_entity_id
> having count(primary_entity_id) = 1
> and is_primary = 0;
>
> This is fine except I want to use the result in a sub-query. Since it
> returns two columns this doesn't work:
>
> update contact_address set is_primary = 1 where address_id in (
> select * from contact_address
> group by primary_entity_id
> having count(primary_entity_id) = 1
> and is_primary = 0
> );
>
> Normally, I'd only return the address_id in the sub-SELECT, but I
> need the is_primary column for the HAVING clause.
I did some tests, and it looks like you can use aggregate functions in
your HAVING clause without actually selecting the column. So "HAVING
COUNT(primary_entity_id) = 1" should work even if you only select
address_id.
--
Dan Nelson
[EMAIL PROTECTED]
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