SQL-query om ontbrekende volgnummers te vinden

Wat dacht je van iets als:

  select (select isnull(max(val)+1,1) from mydata where val < md.val) as [from],
     md.val - 1 as [to]
  from mydata md
  where md.val != 1 and not exists (
        select 1 from mydata md2 where md2.val = md.val - 1)

samenvattende resultaten geven:

from        to
----------- -----------
6           6
8           8
11          14