Count ISNULL convert to varchar-CodePudding

I have this query

SELECT   
    COUNT(ISNULL(TRY_CAST(item AS nvarchar), 'Unknown')) AS [col], 
    item
FROM
    table1
GROUP BY
    item

And I get this result:

col item
---------
2   NULL
1   100

Not sure why NULL won't change to 'Unknown'.

Can you point out the wrong query? Thank you

CodePudding user response：

Your select statement is off, and you presumably wanted this:

SELECT ISNULL(TRY_CAST(item AS nvarchar), 'Unknown') AS item, COUNT(*) AS cnt
FROM table1
GROUP BY ISNULL(TRY_CAST(item AS nvarchar), 'Unknown');