INF: How to Downgrade From SQL Server 6.5 Service Pack 5 or 5a

Service Packs 5 and 5a for SQL Server 6.5 are more comprehensive service packs than previous SQL Server service packs. In addition to updating the SQL Server files, SP5 and SP5a install Microsoft Distributed Transaction Coordinator (DTC) 2.0, which is the version of DTC that is included with Windows NT 4.0 SP4 and SQL Server 7.0. SQL Server 6.5 SP5 and SP5a include Microsoft Data Access Components (MDAC) version 2.1, although this package is not automatically installed with SP5 or SP5a. If SQL Server is installed with an ANSI code page, SP5 and SP5a also slightly modify the sorting behavior of SQL Server to include support for the new Euro character.

As with all product upgrades, you should test to verify that existing applications work as expected with the service pack you are applying before applying the service pack to a production SQL Server.

SQL Server 6.5 Service Packs 5 and 5a are fully supported by Microsoft. If you do encounter a problem after installing SP5 or SP5a, you should contact Microsoft SQL Server Support. A support professional will work with you to identify the specific cause of the problem and determine the best course for resolving the issue.

However, if you do encounter a change in behavior that is specific to the server-side components of SQL Server, you may be able to return to the behavior you saw in a previous service pack by replacing the relevant SQL Server files with the files from the previous service pack, as described in the following paragraphs.

Changes introduced by SP5 and SP5a that will not be removed by these instructions include:

• Changes to sorting behavior to provide support of the new Euro character. As described in the SP5 and SP5a Readme.txt file, this change should only affect you if you are storing binary data in a char or varchar column and are depending on SQL Server's ordering of that binary data.
  
  
• MDAC 2.1 is included with SP5 and SP5a but not installed by default. There is no way to automatically uninstall MDAC 2.1. However, the MDAC components are only used by client applications running on the server, and they are designed to be backwards compatible with previous versions. If your problem is specific to the version of the SQL Server ODBC driver that is included in MDAC 2.1, you can replace the SQLSRV32.DLL file in the WINNT\SYSTEM32 directory with the previous version of the file.
  
  
• DTC 2.0 is included with SP5 and SP5a and is installed by default. There is no way to automatically uninstall DTC 2.0.
  

NOTE: You may see the following error from SQL Server distribution tasks or other ODBC applications after installing MDAC 2.1: If this is the problem you are experiencing you do not need to uninstall SP5 or SP5a. The problem and its resolution are described in the following Microsoft Knowledge Base article: