BUG: Query UPDATE Fails with IGNORE_DUP_KEY Set (105337)

The information in this article applies to:

Microsoft SQL Server 4.2x
Microsoft SQL Server 6.0
Microsoft SQL Server 6.5
Microsoft SQL Server for OS/2 4.2

This article was previously published under Q105337

BUG# OS/2: 1777 (4.2a)
NT: 505 (4.2), 14895 (6.0/6.5)

SYMPTOMS

On page 226 of the "Transact-SQL Reference" for SQL Server for Windows NT (or page 69 of the "Language Reference Guide" for OS/2), it states:

If IGNORE_DUP_KEY is set and you give an UPDATE or INSERT statement that creates duplicate keys, the row that causes the duplicates is not added or changed. In fact, in the case of UPDATE , the row is discarded.
...However, if the UPDATE or INSERT attempt affects multiple rows, the other rows are added or changed as usual.

When an UPDATE is performed, SQL Server does not behave as explained above. Instead, the UPDATE fails if it will cause a duplicate row in the table.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

For example, table test (name char(10), age int NULL) has a unique clustered key with IGNORE_DUP_KEY on column age:

   Name               Age
   ----------------------

   karl               19
   smith              20
   johns              24
   mary               25

The following query:

     update test
     set age=age+4
     where name not like "%johns%"

fails with the errors:

duplicate key was ignored

-and-

0 rows affected.

According to the manual, it should discard the row smith and update the other two rows (karl and mary) as in the following:

   name             age
   --------------------

   karl             23
   johns            24
   mary             29

Modification Type:	Major	Last Reviewed:	12/3/2003
Keywords:	kbBug kbpending kbProgramming KB105337