SELECT SUM() FROM (SELECT (SELECT ())

Question

I have a correct working T-SQL-script in this form

SELECT  columnA
        AS
        'numbers'
FROM    tableA
WHERE   clause

This script gives me as one column, called numbers, of integers. I want to sum these.

Calling the above lines 'script' I tried the following setup

SELECT  SUM(numbers)
FROM    (
            script
        )

Reading select count(*) from select I supposed this to work, however, it does not. I keep getting "Incorrect syntax near."

I do not know if it is important but that is here named columnA is itself maked by a SELECT statement.

Answer 1

You need an alias on the subquery:

SELECT  SUM(numbers)
FROM    
(
    script  -- your subquery will go here
) src   -- place an alias here

So your full query will be:

select sum(numbers)
from
(
   SELECT  columnA  AS numbers
   FROM    tableA
   WHERE   clause
) src