The Art of SQL Server FILESTREAM - Red Gate Software

Chapter 5: FILESTREAM with ASP.NET and Silverlight{cmd.Transaction = tran;cmd.Parameters.Add(new SqlParameter("itemID",System.Data.SqlDbType.VarChar, 20));cmd.Parameters["itemID"].Value = itemID;using (SqlDataReader dr = cmd.ExecuteReader()){if (dr.HasRows && dr.Read()){using (SqlFileStream sfs = new SqlFileStream(dr.GetString(0),(byte[])dr.GetValue(1), FileAccess.Read)){// This construct is used to avoid problems with a// FILESTREAM data file that exceeds 4 GB in sizems = new MemoryStream((int)System.Math.Min(sfs.Length, int.MaxValue));}}}}}// Copy the SqlFileStream contents to the// MemoryStream (requires .NET 4.0 and later)sfs.CopyTo(ms);}}return ms;Listing 5-15:Code for the ItemData class.In this method, new SqlConnection and SqlTransaction objects are created.Those are then used to retrieve the information necessary to create an instance of theSqlFileStream class. Recall that in Chapter 4, as part of the second Entity Frameworklab, we created a stored procedure that encapsulates this. That stored procedure could bereused here instead of the embedded SQL statement. Then the contents of theSqlFileStream are copied to a new instance of System.IO.MemoryStream,which is then used as the return value of the method.208