Question

I have the following query:

select  count(ords.TRACKING_NUM)
from    Orders ords (NoLock)   
group by ords.TRACKING_NUM
having count(distinct ords.ORDER_NUM) = 4

I want it to retrieve the total amount of TRACKING_NUMs that have 4 ORDER_NUMs on them (should be 3,352). Instead I get 3,352 rows equal to 4 (or more because of the distinct).

I get why this is happening. It is counting the values inside each group by. And I can easily change the query to this:

select  ords.TRACKING_NUM
from    Orders ords (NoLock)   
group by ords.TRACKING_NUM
having count(distinct ords.ORDER_NUM) = 4

and then it get 3,352 rows of TRACKING_NUMs returned to me. However, this is not very performant on my database (takes about 41 seconds). What I really need is a query that will give me a count and only a count (and by doing that hopefully go faster).

Thanks for any suggestions.

Answer 1

SELECT COUNT(*)
FROM (
   SELECT TRACKING_NUM
   FROM Orders
   GROUP BY TRACKING_NUM
   HAVING count(distinct ORDER_NUM) = 4) AS Agg