Select Distinct Value from Multiple tables, Where One has Multiples

Question

I have searched for this problem but have not found anything quite like it. I have two tables, both with a field, FormID. In table A, FormID is unique. In table B, there can be multiple records with the same FormID -- table B is a problem tracker table, so if there are multiple data entry problems in the form, there will be multiple records in there.

The following query works:

select distinct b.FormID
from b
where b.FormID = a.FormID
and a.status='done'

as far it does generate a result list of unique FormIDs. However, I also need to get some other columns in this query and it's when I add those columns to the select or the join that I get ALL the duplicate FormIDs.

I have tried:

select distinct (b.FormID), a.FormType, a.Site, a.uid, b.ProbID, b.Date
from b, a
where b.FormID = a.FormID
and a.status='done'

as well as a couple of variations using joins, but they all end up with all the rows with duplicate FormIDs.

Suggestions?

Answer 1

Try

SELECT  b.FormID, 
        MAX(a.FormType) FormType, 
        MAX(a.Site) Site, 
        MAX(a.uid) uid, 
        MAX(b.ProbID) ProbID, 
        MAX(b.Date) Date
  FROM b INNER JOIN 
       a ON b.FormID = a.FormID
 WHERE a.status='done'
 GROUP BY b.FormID