SQL Server Data Types and ADO.NET
SQL Server and the .NET Framework are based on different type systems, which can result in potential data loss. To preserve data integrity, the .NET Framework Data Provider for SQL Server (System.Data.SqlClient) provides typed accessor methods for working with SQL Server data. You can use the enumerations in the SqlDbType classes to specify SqlParameter data types.
For more information and a table that that describes the data type mappings between SQL Server and .NET Framework data types, see SQL Server Data Type Mappings.
SQL Server 2008 introduces new data types that are designed to meet business needs to work with date and time, structured, semi-structured, and unstructured data. These are documented in SQL Server 2008 Books Online.
The SQL Server data types that are available for use in your application depends on the version of SQL Server that you are using. For more information, see the relevant version of SQL Server Books Online in the following table.
SQL Server Books Online