SQL Server: How to add count to nested select - sql

Question

I have two tables, one containing a list of files and one containing a list of tags which are linked by a fileID.
Currently I select this as follows which works fine so far.
How do I have to amend this if I want to count the tags per file and show this in addition to the selected data ?
What I want to do is show how many tags are assigned to each file.
My SP:
SELECT C.fileTitle,
C.fileID,
(
SELECT T.fileTag
FROM Files_Tags T
WHERE T.fileID = C.fileID
ORDER BY T.fileTag
FOR XML PATH(''), ELEMENTS, TYPE
) AS tags
FROM Files C
ORDER BY C.fileTitle
FOR XML PATH('files'), ELEMENTS, TYPE, ROOT('root')
Many thanks for any help with this, Tim.

Answer 1

You can add a subquery:
SELECT C.fileTitle,
C.fileID,
(
SELECT COUNT(*)
FROM Files_Tags T
WHERE T.fileID = C.fileID
) AS NumTags,
(
SELECT T.fileTag
FROM Files_Tags T
WHERE T.fileID = C.fileID
ORDER BY T.fileTag
FOR XML PATH(''), ELEMENTS, TYPE
) AS tags
You could also put in a join and aggregation in the outer query. But, your query already has to use a nested select for the concatenation, so you might as well use the same structure for the count.

Answer 2

Can't you just do this?:
SELECT C.fileTitle,
C.fileID,
(
SELECT T.fileTag
FROM Files_Tags T
WHERE T.fileID = C.fileID
ORDER BY T.fileTag
FOR XML PATH(''), ELEMENTS, TYPE
) AS tags,
(
SELECT
COUNT(*)
FROM
Files_Tags T
WHERE
T.fileID = C.fileID
) AS NumberOfTages
FROM Files C
ORDER BY C.fileTitle
FOR XML PATH('files'), ELEMENTS, TYPE, ROOT('root')
Anding a sub query for the count