Question

I’m trying to select MerchantIDs that are the same but have different Networks values, for example:

ID   MerchantID   Network 
1    1            A 
2    1            A 
3    2            B 
4    2            C 
5    3            D 
6    3            D

In that case I would like the query to return “2” (since it’s the only MerchantID that have different Networks).

Until now I have the following query:

SELECT   a.MerchantID
FROM     table a
JOIN   table b
ON  a.ID = b.ID
AND a.Network <> b.Network
AND a.MerchantID = b.MerchantID 
GROUP BY a.MerchantID

Thing is table have around ~43,000 records and that query takes a LOT of time (haven’t been even able to get the results).

Is there any better way to do it?

Thanks.

Answer 1

Try this:

SELECT MerchantID
FROM yourtable
GROUP BY MerchantID
HAVING COUNT(Distinct Network)>1

this should be faster, joins that use <> conditions are (usually) slower.