Question

Im trying to get the time difference between two values in a table and eliminate all NULLs.

SELECT NumberOfMinutes =
   DATEDIFF(millisecond, tbl_hugo_game.time_start, tbl_hugo_game.time_end)
FROM tbl_hugo_game 
WHERE numberofminutes <> NULL 
ORDER BY numberofminutes ASC

without the WHERE-clause it is working fine,
otherwise :

Msg 207, Level 16, State 1, Line 3
Invalid column name ‘numberofminutes’.

What’s wrong?

Answer 1

You cannot use column aliases in a where clause.

You can, however, put the query with the alias as a source for another query, like this:

select * from (
  select DATEDIFF(...) AS NumberOfMinutes 
  FROM tbl_hugo_game) source
where NumberOfMinutes is not null 
order by NumberOfMinutes asc