LISTING 1: Code to Find Missing Identity Values

SELECT * FROM
     (SELECT *, '+' + CONVERT(varchar,(SELECT MIN(regionid) FROM region
      WHERE regionid > A.regionid) - (regionid + 1)) 'DIFFERENCE' FROM
      region A WHERE (SELECT MIN(regionid) FROM region WHERE regionid >
      A.regionid) - regionid >= 2
UNION ALL
SELECT *, '-' + '' 'DIFFERENCE' FROM region A
     WHERE regionid - (SELECT MAX(regionid) FROM region WHERE regionid <
     A.regionid) >=  2) AS OUTER_TAB
ORDER BY 1, CASE [DIFFERENCE]  WHEN '-' THEN 0 ELSE [DIFFERENCE] END