SQL Server was originally the Microsoft rebadged version of the Sybase relational database. It is only available on Windows platforms. Current version (July 2010) is SQL Server 2008 R2. The two principal differences between SQL Server/Sybase and Oracle are: 1. SQL Server has no undo or rollback segments and therefore no rollback/commit functionality, or read consistent data views; other than what little can be accommodated from the on line redo logs. 2. SQL Server architecture is: 1 host machine to 1 or more Instances to many Databases. There is no such thing as a tablespace within SQL Server. On line redo logs exist.
