Problem with LIMIT & IN/ALL/ANY/SOME subquery

Question

I have this query:

SELECT count(cp.CxID) as intSmokers 
FROM CustPrimarySmoking cp 
JOIN Customer c ON cp.CxID = c.CustomerID 
WHERE 
cp.CxID IN (SELECT CxID         


        

Answer 1

This limitation is a pain if you want to get something like "top N rows for each group". But in your case I wouldn't use that feature even if it were possible. What you try to do is to count all rows except of one row each CxID. All you need is just to subtract the number of distinct CustomerIDs, which is count(DISTINCT cp.CxID). So your final query should be as simple as:

SELECT count(cp.CxID) - count(DISTINCT cp.CxID) as intSmokers 
FROM CustPrimarySmoking cp