Keeping up with new data-access enhancements in Visual Studio (VS) is a full-time job for SQL Server database developers. VS 2008 and the .NET Framework 3.5 SP1 include these new SQL Server data-access options.

6. ADO.NET 3.5
ADO.NET 3.5 supports SQL Server 2008 data types including the date, time, hierarchical, geospatial, and FileStream data types. ADO.NET supports database connectivity using the native SQL Server .NET Data Provider but can also connect to SQL Server and other databases using the Microsoft OLEDB Provider, and the ODBC driver.

5. LINQ to DataSet
LINQ to DataSet combines the new LINQ syntax with the ADO.NET DataSet object. Unlike ADO.NET where you wrap SQL statements with ADO.NET objects, LINQ is a new data-access technology that enables you to construct queries directly in Visual Basic (VB) or C#, eliminating the dual development methodology used in ADO.NET. LINQ to DataSet uses the ADO.NET DataSet’s cache for schema and storage and is useful for building n-tiered web applications. It works with all SQL Server versions and any other databases where there is a .NET Data Provider.

4. LINQ to SQL
Using the LINQ programming model, LINQ to SQL enables database developers to directly access SQL Server 2008 and SQL Server 2005 databases. You must first create an object-level representation of the relational database, either manually or by using a tool (see the SQLMetal code-generation tool at msdn.microsoft.com/en-us/library/bb386987.aspx or the Object Relational Designer—O/R Designer—visual design surface at msdn.microsoft.com/en-us/library/bb384429.aspx). You then use the object-relational model you created along with the LINQ programming model to query and update SQL Server databases.

3. ADO.NET Entity Framework
ADO.NET Entity Framework goes beyond the capabilities offered by LINQ to SQL. While LINQ to SQL is limited to SQL Server databases and provides a simple one-to-one mapping between relational database objects and program objects, the ADO.NET Entity Framework lets you create a full conceptual model across the enterprise. It consists of the Entity Data Model (EDM), which maps the model to the data store, and the Entity Framework, where you use Object Services, Entity Client, Entity SQL or LINQ to Entities to access the EDM.

2. ADO.NET Data Services
ADO.NET Data Services (code-named Astoria) addresses the problem of accessing your data online. It exposes an object model and is accessed using the REST protocol. Data can be consumed by a .NET Framework 3.5 client, by Silverlight 2, and also by ASP.NET AJAX clients.

1. SQL Server Data Services
VS 2008 developers can also use SQL Server Data Services (SSDS), essentially a data store in the cloud. Data is exposed using the REST or SOAP protocols, enabling SSDS to be accessed by both .NET and other technologies such as Java that support these protocols.