One of the tasks in planning a SQL Server deployment is choosing the right combination of SQL Server editions, based on your application's scalability, availability, performance, and advanced analysis requirements. You can choose from the following SQL Server 2005 editions:
Enterprise Edition This edition includes the complete set of SQL Server data management and analysis features and is uniquely characterized by several features that make it the most scalable and available edition of SQL Server 2005. This edition has no limit on the number of processors or amount of memory or database size. It includes all the performance, scalability, high-availability, security, manageability, programmability, integration and interoperability, and business intelligence features, making it a comprehensive data and analysis platform for large, mission-critical business applications.
Standard Edition This edition is a complete data and analysis platform, and it is designed for medium-sized businesses. It places no limit on the amount of memory or the database size, but the number of processors is limited to four. Standard Edition includes high-availability features such as database mirroring and failover clustering, but it does not support online indexing or online page or file restores. Some of the business intelligence features, such as proactive caching and text mining, are turned off in Standard Edition. Standard Edition does not support partitioning or parallel index operations.
Workgroup Edition In February 2005, Microsoft announced a new addition to both the SQL Server 2000 and SQL Server 2005 families, called Workgroup Edition. Workgroup Edition is an affordable, easy-to-use, and simple-to-manage database solution designed specifically for small to medium-sized organizations. SQL Server 2005 Workgroup Edition places no limit on the size of the database. However, it is limited to two processors and 3GB of RAM. (SQL Server 2000 Workgroup Edition limits the amount of RAM to 2GB.) Workgroup Edition does not support high-availability features such as database mirroring, clustering, and online indexing, and it lacks most of the other editions' business intelligence features.
Express Edition SQL Server 2005 Express Edition supersedes Microsoft SQL Server 2000 Desktop Engine (MSDE). Like MSDE 2000, SQL Server 2005 Express Edition is a no-cost, freely redistributable version. Unlike MSDE 2000, which does not provide any graphical tools, SQL Server 2005 Express Edition provides graphical tools such as Express Manager and SQL Server Configuration Manager. Unlike MSDE 2000, SQL Server 2005 Express Edition does not implement a "concurrent workload throttle" mechanism to limit the application's scalability under heavy load. Express Edition limits the database size to 4GB, a single processor, and up to 1GB of server memory. Express Edition does not support many features, such as database mirroring, failover, partitioning, and online index operations, and it does not bundle tools such as SQL Server Management Studio and Profiler.
Mobile Edition Microsoft SQL Server 2000 Windows CE 2.0, also known as SQL Server CE, is being superseded by SQL Server 2005 Mobile Edition. This edition can run on table PCs and smart devices, including any device that runs Microsoft Windows CE 5.0, Microsoft Mobile Pocket PC 2003, Microsoft Mobile Version 5.0 Pocket PC, or Microsoft Mobile Version 5.0 Smart Phone. SQL Server 2005 Mobile Edition includes a set of relational database features while maintaining a compact footprint. This edition contains several significant advancements over SQL Server CE.
Evaluation Edition This time-limited trial version, which contains the same features as Enterprise Edition, is available only for testing and evaluation purposes and should not be deployed in production.
Developer Edition This edition contains the same features as Enterprise Edition, but it is intended only for development purposes and should not be deployed in production.
As you can see, SQL Server 2005 provides the flexibility to acquire the right combination of SQL Server technologies to meet your needs. Once you know which SQL Server editions you need, the next step is to figure out the hardware and software requirements for installing each edition.