Fix: Error 130: Cannot perform an aggregate function on an expression containing an aggregate or a subquery
Following statement will give the following error: “Cannot perform an aggregate function on an expression containing an aggregate or a subquery.” MS SQL Server doesn’t support it.
USE PUBS
GO
SELECT AVG(COUNT(royalty)) RoyaltyAvg
FROM dbo.roysched
GO
You can get around this problem by breaking out the computation of the average in derived tables.
USE PUBS
GO
SELECT AVG(t.RoyaltyCounts)
FROM
(
SELECT COUNT(royalty) AS RoyaltyCounts
FROM dbo.roysched
) T
GO
Reference : Pinal Dave (https://blog.sqlauthority.com) , BOL.
