Question

I need to write a query which would always return something, even if nothing satisfies conditions, something like this

SELECT * WHERE date > NOW() FROM table ORDER by date
   IF none is returned THEN
      SELECT FIRST FROM table ORDER by date

So only numbers more then 10 will be returned, if none is returned, return any number
Any ideas how to do it?

Answer 1

Here is one way, using union all:

select *
from table
where number > 10
union all
(select *
 where number > 0 and
       not exists (select * from table where number > 10)
 limit 1
)

If you are using a reasonable version of SQL, you could do something like:

select t.*
from (select t.*, max(number) over () as maxnumber,
             row_number() over (order by number desc) as seqnum
      from table t
     ) t
where (maxnumber > 10 and number > 10) or seqnum = 1

You need window functions for this.