Question

I have multiple SELECT queries unioned. The composite primary key is preventing duplicates, which is what I want. Is there a way to increment a certain field whenever a duplicate row is prevented from being inserted from one of the unioned queries?

Answer 1

You could use UNION ALL to retain the duplicates, then group the result with an outer query:

SELECT a, b, c, COUNT(*)
FROM (
  SELECT a, b, c FROM ...
  UNION ALL
  SELECT a, b, c FROM ...
) AS t
GROUP BY a, b, c