Answers for "how do you remove duplicate columns from postgres join"

query postgres delete duplicates

DELETE FROM dups a USING (
      SELECT MIN(ctid) as ctid, key
        FROM dups 
        GROUP BY key HAVING COUNT(*) > 1
      ) b
      WHERE a.key = b.key 
      AND a.ctid <> b.ctid

postgres select duplicate columns

select * from yourTable ou
where (select count(*) from yourTable inr
where inr.sid = ou.sid) > 1