postgres no duplicates in query] code example

Example 1: postgres select duplicate columns

select Column1, Column2, count(*)
from yourTable
group by Column1, Column2
HAVING count(*) > 1

Example 2: 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