FIX: A conflict with the foreign key constraint occurs when you update the case of the column values in the primary key table or you pad column values in the primary key table in SQL Server 2005

When you update the primary key column of the primary key table in Microsoft SQL Server 2005 by changing the case of the existing column values or by padding column values, you receive the following error message:For example, this problem occurs in both the following situations.

Example 1

• You create two tables by using a case-insensitive collation such as the SQL_Latin1_General_CP1_CI_AS collation.
• You build a primary key and foreign key relationship between these two tables.
• You update the primary key column of the primary key table by changing the case of the existing column values.

Example 2

• You create two tables.
• You build a primary key and foreign key relationship between these two tables.
• The ANSI_PADDING setting is set to OFF.
  
  Note By default, the ANSI_PADDING setting is set to OFF.
• You update the primary key column of the primary key table by padding the column values.

This problem occurs because values that are equal at the type level may be distinct at the binary level.

For example, at the type level, N'a' is equal to N'A'. However, at the binary level, N'a' is not equal to N'A'. The optimization mechanism incorrectly assumes that the update operation that changes the case does not make any real changes. Therefore, the PK-FK check is unsuccessful.

Service pack information

To resolve this problem, obtain the latest service pack for SQL Server 2005. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in SQL Server 2005 Service Pack 3.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: