If you’re a SQL Server 2005 Express user, you’ll definitely want to learn about the major changes Microsoft has made to the follow-on product: SQL Server 2008 Express Edition. Although there are more new features than I can cover here, I’ll show you some of the biggest and best. SQL Server 2008 Express will be completely compatible with all the applications you’re running with SQL Server 2005 Express; moving to SQL Server 2008 Express requires no application changes.

From a hardware standpoint, SQL Server 2008 Express will have the same requirements and limitations as SQL Server 2005 Express. The new product will still run on a system that has just one CPU and 1GB of memory, and it will still support multiple databases of up to 4GB.

From the database engine perspective, SQL Server 2008 Express Edition will provide several new data types: Date, Time, DateTime2, DateTimeOffset, Geography, Geometric, and Filestream. As their names suggest, the Data and Time data types give you an alternative to the older datetime data type, which combined both date and time information in a single column. DataTime2 provides increased time accuracy, and DateTimeOffset provides time-zone-aware storage for date and time values. The Geography and Geometric data types provide location-aware storage and are useful for mapping applications. The FileStream data type lets you store line-of-business (LOB) data in the file system outside of the SQL Server Express database while SQL Server maintains the links between the external LOB data and the database.

An important architectural improvement is the inclusion of the new Resource Governor, which lets you put a limit on the system resources that a given query can consume. T-SQL also has several new features, including a new MERGE statement that combines insert, update, and delete capabilities. Support for table value parameters lets you pass tables to stored procedures as parameters.

For the developer, SQL Server 2008 Express shares the same productivity enhancements that are slated for the full-featured editions of SQL Server 2008, such as a new ADO.NET Entity Framework and support for Language Integrated Query (LINQ). The ADO.NET Entity Framework and LINQ make database application development fully object-oriented and more productive. Keep in mind that, in order to take advantage of LINQ, you need to have the .NET Framework 3.5. If you don’t already have Visual Studio 2008, a good place to get the new .NET Framework is with one of the free Visual Studio Express products.

With its host of new features, SQL Server 2008 Express promises to provide a great upgrade path for SQL Server 2005 Express users. You can download the latest SQL Server 2008 Express Community Technology Preview (CTP).