I tried and I got another error for both @mytable and TestCategory

Error:

Msg 102, Level 15, State 1, Line 4

Incorrect syntax near '.'.

And I tried with select after cross apply. Again got the same error.

select D.Item as [Category], COUNT(*) AS Count

from dbo.TestCategory as T

cross apply

(

select * from dbo.fnSplit(T.[Category],'/')

) as D

group by D.Item

I test the fnSplit() function and it's returning correct values

select * from dbo.fnSplit('asp.net/c#/xml/html','/')

Returns

Item Number---Item

1----------------asp.net

2----------------c#

3----------------xml

4----------------html