FIX: Using a WHERE IN Clause on a Selected UNION May Fail (162366)

SYMPTOMS

SELECT statements consisting of a UNION and a WHERE IN clause may fail.

For example, the following statement

   SELECT type, name
      FROM (SELECT * FROM master..sysobjects
                UNION
                SELECT * FROM pubs..sysobjects) as O
      WHERE type IN ('S', 'U')

Produces (in part) the following results:

  type name
  ---- ------------------------------
  U    authors
  P    byroyalty
  C    CK__authors__au_id__02DC7882
  C    CK__authors__zip__04C4C0F4
  C    CK__jobs__max_lvl__2719D8F8
  C    CK__jobs__min_lvl__2625B4BF
  C    CK__publisher__pub_i__089551D8
  C    CK_emp_id

WORKAROUND

Embed SELECT statements into the WHERE IN clause, as shown by the following:

   SELECT type, name
      FROM (SELECT * FROM master..sysobjects
         UNION
         SELECT * FROM pubs..sysobjects) as O
      WHERE type IN (SELECT 'S' UNION SELECT 'U')

STATUS

Microsoft has confirmed this to be a problem in Microsoft SQL Server version 6.5 Service Pack 1. This problem has been corrected in U.S. Service Pack 2 for Microsoft SQL Server version 6.5. For more information, contact your primary support provider.