Microsoft's SQL Server is a suite of relational database management system (RDBMS) products providing multi-user database access functionality. It originated from Sybase SQL Server 4.x codebase and Transact-SQL dialect (T-SQL), but forked significantly since then.
SQL Server is available in multiple versions, typically identified by release year, and versions are subdivided into editions to distinguish between product functionality. The latest released version is SQL Server 2012.
The SQL Server product range is split broadly into 4 categories:
Category 1 : SQL Server : Main editions include Enterprise, Business Intelligence and Standard editions. There is also Web Edition that can only be purchased by web hosting companies. Primary differences are
- Licensing costs capacities, and components included in the product
- Some minor differences supported language features
Standard components include
- DB Language and storage server
- Developer tools
- ETL tools
- Other components
- Parallel Computation
Components runs as NT Services.
Category 2 : SQL Server Express : Free for use and distribution but reduced engine performance, functionality and capacity than found it's other server siblings. Focused on small deployments. Runs as an NT Service. Great for migrating data from small system/projects whose main storage was MS Access, thus providing a upward path for expansion into the more robust SQL Server suite.
Category 3 : SQL Server Compact an embeddable subset of SQL Server. Like Express edition is has reduced language, functionality and capacity, but is free to distribute. It's focused on small installations and desktop applications where it's small footprint and no-management-required features are a great advantage.
Category 4 : SQL Azure completely managed, hosted, high-availability instance of SQL Server 2005 with some language syntax support federated query, operated in Microsoft Azure datacenters.