What you want is COUNT(DISTINCT <expression>) : evaluates expression for each row in a group and returns the number of unique, non-null values. ... <看更多>

Difference between COUNT (*) , COUNT(1), COUNT(Col_Name) and COUNT ( Distinct (Col_Name) in SQLThis is very important SQL Interview Question ... ... <看更多>

This is how I'd do it: SELECT * FROM #MyTable AS mt CROSS APPLY ( SELECT COUNT(DISTINCT mt2.Col_B) AS dc FROM #MyTable AS mt2 WHERE mt2. ... <看更多>

I need to count both the total number of items in a group and the unique values in the grouped fields. Using .Distinct() on the group ... ... <看更多>