The Microsoft SQL ServerSwitch Program Group
The second program group, available only on Windows NT and Windows 2000 installations of SQL Server 2000, contains three possible options. These options are the SQL Server Version Upgrade Wizard, the uninstall utility, and possibly a SQL Server 6.x switch.
SQL Server Version Upgrade Wizard
You examined the Version Upgrade Wizard yesterday when you learned about installing SQL Server 2000. SQL Server Version Upgrade on Windows NT computers enables you to upgrade SQL Server 6.5 databases and server properties. You can upgrade a single database, multiple databases, or server and scheduled job properties from a previous release of SQL Server.
SQL Server versions 6.5 and 7.0 are the only releases supported for upgrade. No other previous releases are supported. SQL Server 7.0 can upgrade in place, so no upgrade wizard is required. You will find the version upgrade utility only on Windows NT/2000 systems because version 6.5 of SQL Server ran only on Windows NT or Windows 2000.
The version upgrade process leaves your SQL Server 6.5 database files in place. When you upgrade, the data is exported from SQL Server 6.5 into SQL Server 2000, and new databases and files are created in SQL Server 2000. You can upgrade your previous installation of SQL Server on the same computer, or you can install SQL Server 2000 on a second computer and then upgrade into the new SQL Server 2000 computer.
Microsoft SQL Server 6.x Switch
The Microsoft SQL Server 6.x Switch program group entry is present only on systems that had SQL Server 6.5 installed. When you click this option, you switch back to your SQL Server 6.5 installation. Your Start menu changes to reflect the SQL Server 6.5 utilities (although your SQL Server 2000 tools are also available), and the previous release of SQL Server is available to run. When you run SQL Server 6.5, the entry in the Switch menu is renamed to Microsoft SQL Server 2000. When you select it again, you return to SQL Server 2000, and your SQL Server 6.5 tools are again hidden.
These options apply only to switching between SQL Server 6.5 and a default instance of SQL Server 2000. As we noted yesterday, you can have SQL Server 6.5, SQL Server 7.0, or SQL Server 2000 as a default instance, with as many named instances as you want to install always running (up to 16 total).
Uninstall SQL Server 6.x
The Uninstall SQL Server 6.x program group entry is present only on systems with a previous release of SQL Server installed. When you click this option, you uninstall your previous release of SQL Server. This custom uninstall program safely removes your previous release of SQL Server.
Don't run setup to remove your old release of SQL Server 6.5. Using the custom uninstaller installed with SQL Server 2000 is the only safe way to remove the previous release without potentially damaging your SQL Server 2000 installation.