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FIX: Select Distinct Fails to Eliminate Duplicate Null Values on Bit Datatype

This article was previously published under Q281338
This article has been archived. It is offered "as is" and will no longer be updated.
BUG #: 26147 (SQLBUG_70)
Select distinct does not eliminate duplicate null values that are contained in bit datatype columns.
Microsoft has confirmed this to be a problem in SQL Server 7.0. This problem has been corrected in U.S. Service Pack 3 for Microsoft SQL Server 7.0. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
274799 INF: How to Obtain Service Pack 3 for Microsoft SQL Server 7.0 and Microsoft Data Engine (MSDE) 1.0
For more information, contact your primary support provider.
Use the code that follows to reproduce this behavior:
create table #myTable( bar bit)goinsert into #mytable values (1)insert into #mytable values (1)insert into #mytable values (NULL)insert into #mytable values (NULL)goselect distinct bar from #mytablego				
The preceding code returns this result:
bar  ---- NULLNULL1				
Note that the code correctly eliminates the duplicate value 1 but incorrectly returns duplicate null values. The correct resultset is:
bar  ---- NULL1				

Article ID: 281338 - Last Review: 10/21/2013 04:33:43 - Revision: 2.1

Microsoft SQL Server 7.0 Standard Edition

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