Question

I have a table with columns user_id, time_stamp and activity which I use for recoding user actions for an audit trail.

How can I COUNT the number of unique user_id where time_stamp=0 when there might be multiple such rows, differing only in in the activity text?

Answer 1

Sounds like you need to use:

  SELECT COUNT(DISTINCT t.user_id)
    FROM YOUR_TABLE t
   WHERE t.time_stamp = 0
GROUP BY t.activity