Hi,
You can use one of windowing function:
this could be rank() in subquery or first_value(vale any), but there could be performance issue
another solution could be boolean flag "default" in table address_reference which should be unique for single company, I mean value true should be unique - this could be reached by unique partial index on column refid_companies with condition default = true
hope Your pg version supports windowing functions (as I remember 8.4 and above)
Of course there is a solution with subquery which finds min id in table addresses of each refid_companies in table addresses_reference and this subquery is joined with companies table, but I am afraid this is not the best one.
Regards,
Bartek
2012/3/12 Alexander Reichstadt
<lxr@mac.com>Hi,
the following statement worked on mysql but gives me an error on postgres:
column "addresses.address1" must appear in the GROUP BY clause or be used in an aggregate function
I guess I am doing something wrong. I read the web answers, but none of them seem to meet my needs:
SELECT companies.id,companies.name,companies.organizationkind,addresses.address1,addresses.address2,addresses.city,addresses.zip FROM companies JOIN addresses_reference ON companies.id=addresses_reference.refid_companies LEFT JOIN addresses ON addresses_reference.refid_addresses=addresses.id GROUP BY companies.id;
What I did now was create a view based on above statement but without grouping. This returns a list with non-distinct values for all companies that have more than one address, which is correct. But in some cases I only need one address and the problem is that I cannot use distinct.
I wanted to have some way to display a companies list that only gives me the first stored addresses related, and disregard any further addresses.
Is there any way to do this?
Thanks
Alex