How to find “holes” in a table

Question

I recently inherited a database on which one of the tables has the primary key composed of encoded values (Part1*1000 + Part2).
I normalized that column, but I cannot ch

Answer 1

This will give you the complete picture, where 'Bottom' stands for gap start and 'Top' stands for gap end:

    select *
    from 
    ( 
       (select +1 as id, 'Bottom' AS 'Pos' from  /*where 
       except
       select , 'Bottom' AS 'Pos' from  /*where */)
    union
       (select -1 as id, 'Top' AS 'Pos' from  /*where */
       except
       select , 'Top' AS 'Pos' from  /*where */)
    ) t
    order by t.id, t.Pos

Note: First and Last results are WRONG and should not be regarded, but taking them out would make this query a lot more complicated, so this will do for now.