Paul White NZ (5/3/2010)

---

Hugo Kornelis (5/3/2010)

---

Using ISNULL can work around this - although the result is admittedly not trivial to understand:
AND NULLIF(Column1, Column2) IS NULL
AND NULLIF(Column2, Column1) IS NULL

Hugo!!! Yuk!

WHERE Column18 > 27
AND (Column1 = Column2 OR (Column1 IS NULL AND Column2 IS NULL))

WHERE Column18 > 27
AND NULLIF(Column1, Column2) IS NULL
AND NULLIF(Column2, Column1) IS NULL

DECLARE @t TABLE(fl int);

INSERT INTO @t VALUES (0);

DECLARE @var CHAR(1),
	@var2 DATETIME
SET @var = ''
SET @var2 = GETDATE()

select nullif(fl, @var)
FROM @t
--Compute Scalar(DEFINE[Expr1004]=CASE WHEN [fl]=CONVERT_IMPLICIT(int,[@var],0) THEN NULL ELSE [fl] END))

select nullif(fl, @var2) 
FROM @t
--Compute Scalar(DEFINE[Expr1004]=CASE WHEN CONVERT_IMPLICIT(datetime,[fl],0)=[@var2] THEN NULL ELSE [fl] END))