HOW TO: Read and Write a File to and from a BLOB Column by Using Chunking in ADO.NET and Visual C++
This step-by-step article describes how to use the Microsoft SQL Server READTEXT and UPDATETEXT statements to read and write data from BLOB (LongVarBinary) columns in a database table.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;317044