Question

I have an simple question (?) about SQL. I have come across this problem a few times before and I have always solved it, but I’m looking for a more elegant solution and perhaps a faster solution.

The problem is that I would like to select all rows in a table except the one with the max value in a timestampvalue (in this case this is a summary row but it’s not marked as this is any way, and it’s not releveant to my result).

I could do something like this:

select * from [table] t
where loggedat < (select max(loggedat) from [table] and somecolumn='somevalue')
and somecolumn='somevalue'

But when working with large tables this seems kind of slow. Any suggestions?

Answer 1

If only you don’t mind one tiny (4 byte) extra column, then you might possibly go like this:

SELECT *
FROM (
  SELECT *, ROW_NUMBER() OVER (ORDER BY loggedat DESC) AS rownum
  FROM [table] t
  WHERE somecolumn = 'somevalue'
    /* and all the other filters you want */
) s
WHERE rownum > 1

In case you do mind the extra column, you’ll just have to list the necessary columns explicitly in the outer SELECT.