The underlying database engine within SQL Server 2000 has been improved, enhanced, and rationalized to give users of SQL Server better performance and value. The changes have not been as dramatic as the shift from SQL Server v6.5 to SQL Server v7.0, but there have been a number of significant improvements, such as the following:
New datatypes. Allows developers to produce applications that are richer and offer support for a larger domain of datatypes.
Cascading referential integrity constraints. Enables an application architect to specify that if parent record A is deleted or modified, then all of parent record A's children are updated as well. In the past, this code had to written by hand, and was both time-consuming and troublesome.
Faster differential backups. A differential backup encompasses only the changes (deltas) to a data set. In SQL Server 2000, differential backups are faster, allowing regular differential database backups to be taken without dramatically affecting performance.
Increased flexibility with index creation/options. DBAs can create indexes on computed columns (although some rules must be followed), build ascending or descending indexes, and specify whether to use the tempdb database as the repository for re-sorting the data when an index is created.
Instead-of triggers. This special type of trigger allows a specified command to happen "instead of" the INSERT/UPDATE or DELETE issued to a table.
While not all of these changes relate to the database engine, they describe the points that Microsoft has taken seriously with the latest edition of SQL Server. With performance being one of the biggest metrics that a database vendor can face, Microsoft has provided a strong focus on improving what was already started with SQL Server v7.0.