Trying to modify a monthly report to a weekly. Aspen Sql

Answer 1

Firstly, can you try simplifying your SQL to:

SELECT count(*)
  FROM history h
 WHERE h.period = '0:00:15'
       AND h.request = '1'
       AND h.stepped = '1'
       AND h.ts BETWEEN StartTime AND EndTime
       AND (   (h.name = Tag1Name AND h.value = Tag1Cond) 
            OR (h.name = Tag2Name AND h.value = Tag2Cond));

Other than that, I can't see why you wouldn't get values for two dates in the same month -- unless your data only contained monthly entries, which I'm guessing isn't the case.

Could you post some sample data from the history table?