Microsoft extended support for all editions of SQL Server 7.0 ended on Jan. 11. Considering that this edition was initially replaced 11 years ago by SQL Server 2000 (and there have been three more major releases since), this may not seem to be big news. However, I'm always amazed by the number of DBAs I meet who are still responsible for keeping a few instances of this, or even version 6.5, running in production.
Microsoft has two support phases for its products - mainstream support, which includes the free support options, and extended support. Ending extended support means paid-for support, assisted support, and security updates are no longer available. Extended support is provided for a minimum of 5 years, or 2 years after the second successor product version is released. SQL Server support is available for a significantly longer period than this, however, reflecting the importance and complexity of the platform and any migrations.
Mainstream support for SQL 2000 ended in August 2008, and extended support is scheduled to end in September 2013. SQL 2005 mainstream support is scheduled to end in December 2011, so, from a support cost perspective this is relevant to a lot of companies.
Most DBAs I meet are predominantly running SQL Server 2005 with some 2008/2008 R2, and some 2000 instances. It is rare to find environments that are completely up to date with the latest release for all deployed instances. Migrating to a new database version is a significant undertaking, and, unless the new release has specific functionality for the database applications, there is an understandable reluctance to make the change.
The migration from SQL Server 2000 invalidated some T-SQL coding options as Microsoft strived to conform to ANSI standards. This meant a lot of third-party applications needed to be rewritten, which often has not happened as quickly as expected. Individual databases can run in older compatibility modes that allow version migrations to take place and enable the depreciated code to continue to work. Microsoft also replaced DTS (Data Transformation Services) with SSIS (SQL Server Integration Services) in SQL Server 2005. SQL Server still supports DTS in SQL 2008 R2, although it is fully depreciated in the next release (Denali).
SQL 2005 incorporated a significant database engine rewrite to improve performance; if there is no specific functionality gain for the application from a new version, however, the drive to migration seems to be more hardware-related. 64-bit SQL Server improves scalability and performance for processor and memory, but obviously has related costs.
Microsoft was widely criticized for the slow release timeframe between SQL Server 2000 and 2005. Release frequency has been quicker with 2008, 2008 R2 in 2010, and Denali, which provisionally is scheduled for the end of 2011. The problem is that Microsoft now has a fragmented userbase across many versions, with seemingly little motivation to migrate to the newer platforms. If more users realized the lack of support available, perhaps the older versions finally could be laid to rest.