BOL
"If you have Microsoft® SQL Server™ version 6.5 installed, you can keep the SQL Server version 6.5 installation and also install a default or named instance of SQL Server 2000. No version upgrading is involved; however, version switching can be used to move between SQL Server version 6.5 and SQL Server 2000. In addition, SQL Server 2000 tools are used to control both SQL Server 2000 and SQL Server version 6.5.

Warning After SQL Server 2000 is installed, the SQL Server version 6.5 Trace utility and other earlier tools are no longer available.


To install SQL Server 2000 alongside SQL Server 6.5:

-Keep your SQL Server 6.5 configuration intact.
-Install SQL Server 2000, selecting either a default or named instance in the Instance Name dialog box.
-Switch versions from SQL Server 6.5 to the default instance of SQL Server 2000.

Note Switching from SQL Server 2000 back to SQL Server 6.5 is not recommended
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" Microsoft® SQL Server™ 2000 can be installed on the same computer with Microsoft SQL Server version 6.5, but only one version can be active at one time .

Note Switching between versions is not the same as running multiple instances. For more information, see Working with Instances and Versions of SQL Server.

After the SQL Server Upgrade Wizard finishes the conversion from SQL Server version 6.5, SQL Server 2000 is the active version of SQL Server. If enough disk space exists on your computer, you can keep the SQL Server 6.5 installation intact.

To switch from one version to the other, use the Microsoft SQL Server-Switch application on the Start menu, or run Vswitch.exe .


Important Be sure the SQL Server Upgrade Wizard is finished with its upgrade tasks, before you attempt to switch between the active and nonactive versions of SQL Server.


To switch from SQL Server 6.5 to SQL Server 2000

Command Prompt

How to switch from SQL Server 6.5 to SQL Server 2000 (Command Prompt)
To switch from SQL Server 6.5 to SQL Server 2000

Run Vswitch.exe.
-SwitchTo <65|80>
Determines which version of Microsoft® SQL Server™ 2000 to activate.

-Silent <0|1>
Determines if any user interface or messages are displayed. If 1 is specified, a user interface or messages are not displayed. The default is 0.
Examples
c:\...\vswitch -SwitchTo 80 -Silent 1



Windows

How to switch from SQL Server 6.5 to SQL Server 2000 (Windows)
To switch from SQL Server 6.5 to SQL Server 2000

On the Start menu, point to Programs/Microsoft SQL Server-Switch, and then click Microsoft SQL Server 2000.

SQL Server Setup switches from Microsoft® SQL Server™ 2000 version 6.5 to SQL Server 2000.
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