Joe Celko's SQL for Smarties, 3rd Edition

24.9. Folding a List of Numbers

It is possible to use the Sequence table to give columns in the same row, which are related to each other, values with a little math instead of self-joins.

For example, given the numbers 1 to (n), you might want to spread them out across (k) columns. Let (k = 3) so we can see the pattern.

SELECT seq_nbr,
       CASE WHEN MOD((seq_nbr + 1), 3) = 2
                 AND seq_nbr + 1 <= :n
            THEN (seq_nbr + 1)
            ELSE NULL END AS second,
       CASE WHEN MOD((seq_nbr + 2), 3) = 0
                 AND (seq_nbr + 2) <= :n
            THEN (seq_nbr + 2)
            ELSE NULL END AS third
  FROM Sequence
 WHERE MOD((seq_nbr + 3), 3) = 1
  AND seq_nbr <= :n;

Columns which have no value assigned to them will get a NULL. That is, for (n = 8) the incomplete row will be (7, 8, NULL) and for (n = 7) it would ...