SELECT CategoryID,
CategoryName + Case IsNull(dtSubs.NoOfSub, 0) When 0 Then '' Else ' there are subs' End
FROM Categories c
LEFT JOIN
(
SELECT ParentID, COUNT(*) AS NoOfSub
FROM Categories
GROUP BY ParentID
) dtSubs
ON (dtSubs.ParentID = c.CategoryID)
WHERE (c.ParentID = @CategoryID)