Problem in WHERE clause

Question

So I have a query. It works if I comment out the part checking for the exclusion.

WHERE H.BatchId = 3  AND H.IsExcluded != 1

IsExcluded is a bit field that accepts NULL values.

All the values I'm selecting from are NULL, so that SHOULD be right. What am I doing wrong? It's returning no values the way it is, but if I comment out just the 'AND' and after, it works.

Answer 1

WHERE H.BatchId = 3  AND (H.IsExcluded != 1 OR H.IsExcluded IS NULL)

Answer 2

in SQL NULL != NULL as @scott said but if can be if you SET ANSI NULL OFF

Declare @a INT = NULL
Declare @b INT = NULL
SET ANSI_NULLS OFF
IF(@b = @a)
    PRINT 'NULL is eaqul to NULL'
ELSE
        PRINT 'NULL is not eaqul to  NULL'

SET ANSI_NULLS ON
IF(@b = @a)
    PRINT 'NULL is eaqul to NULL'
ELSE
        PRINT 'NULL is not eaqul to  NULL'

Output is NULL is eaqul to NULL --> Here SET ANSI_NULLS OFF is done NULL is not eaqul to NULL--> Here SET ANSI_NULLS ON is done. By default SQL Server has this setting