This article previously appeared in Windows NT Magazine.

The many versions of SQL Server 7.0 can be confusing, so we thought a brief marketing-free summary might be helpful to readers. We begin at the high end with SQL Server 7.0 Enterprise Edition, which works only if you've installed Windows NT Server 4.0, Enterprise Edition (NTS/E). SQL Server 7.0 Enterprise Edition includes clustering support. This feature lets you set up two-node failover managed by Microsoft Cluster Server (MSCS), which is an attractive feature for environments that require high availability. Enterprise Edition also includes support for extended memory that is available on Alpha and other 64-bit systems. Finally, this version lets you set up online analytical processing (OLAP) partitions in OLAP Services. These partitions let SQL Server split OLAP cubes among different servers for enhanced scalability and manageability.

The next version is SQL Server 7.0 Standard Edition, which Microsoft designed to be SQL Server's mainstream server installation. Standard Edition runs on only NT Server 4.0 with Service Pack 4 (SP4) or later. Standard Edition ships with OLAP Services.

SQL Server 7.0 Standard Edition also comes with Desktop Edition, which runs on NT Workstation 4.0 with SP4 or later and Pentium-class Windows 9x systems. SQL Server Desktop Edition can't run OLAP Services, but this version runs Pivot Table Services, the OLAP client software. Can you use Desktop Edition running on a Win9x system as a server solution for small workgroups? In theory, the answer is yes. However, we don't recommend this setup. Desktop Edition can't match the performance of Standard Edition, mainly because Desktop Edition doesn't support asynchronous I/O.

When you buy a SQL Server Client Access License (CAL), you receive a fully licensed copy of SQL Server 7.0 Desktop Edition. You don't have to install the whole server if you don't need the capability, but this licensing scheme provides companies with a cost-effective method to roll out mobile applications based on SQL Server 7.0.

The NT BackOffice Small Business Server (SBS) 4.5 version of SQL Server 7.0 is basically the same as SQL Server 7.0 Standard Edition, and supports SQL Server 7.0's alternative per-seat licensing model. In the past, SBS didn't support the same service packs as other SQL Server versions, which made maintenance difficult. Microsoft has added consistent rollout of service packs for both Standard Edition and the SBS version of SQL Server 7.0. In addition to improved service pack synchronization, the SBS version includes support for larger databases (SQL Server's initial SBS edition limited you to 1GB databases) and more users (Microsoft increased SQL Server 7.0's SBS version user support from 50 to 100 users).

Microsoft Office 2000 and Microsoft Access 2000 will include a new lean version of SQL Server called the Microsoft Database Engine (MSDE). This lean edition is a special version of SQL Server that Access 2000 will natively support and Microsoft will embed in all future versions of Microsoft Visual Studio and several other products. You can think of MSDE as a subset of SQL Server. The SQL Server development team created this lean version, which will be the long-term replacement for Jet. MSDE doesn't provide management tools or the GUI tools necessary to interactively design Data Transformation Services (DTS) packages; however, MSDE lets you execute these packages. You won't want to use MSDE with more than five or six concurrent users. To support more users, Microsoft wants you to buy the real thing.