The Art of SQL Server FILESTREAM - Red Gate Software

Chapter 3: Accessing FILESTREAM Data from Client ApplicationsSqlFileStream Class ReferenceThe SqlFileStream class represents the FILESTREAM data file associated with theBLOB data stored in a FILESTREAM cell. This class exposes the BLOB as a sequenceof bytes.SqlFileStream is derived from System.IO.Stream and resides in the System.Data.Sqltypes namespace. To use the SqlFileStream class, you need a referenceto assembly System.Data in System.Data.dll. (SqlFileStream was added to theFramework with.NET Framework 3.5 SP 1 or later, which also includes 2.0 SP 2 and3.0 SP 2.)Instantiating a SqlFileStream objectSqlFileStream provides two constructors that you can use to instantiate an object withdifferent levels of control over the file being accessed. We have seen an example of thebasic constructor earlier in this chapter. Listing 3-34 shows the simple constructor that wesaw earlier.// Open and read file using SqlFileStream ClassSqlFileStream fs = new SqlFileStream(filePath, txContext, FileAccess.Read);Listing 3-34:C# code that opens a FILESTREAM data file for read access.• filePath – This is the logical path to the physical file associated with theFILESTREAM data value. The logical path is retrieved by a call to the PathName()function on the FILESTREAM column on the specific row in the table.• txContext – This is the FILESTREAM transaction context associated with the currenttransaction. Note that you need an active transaction even to read FILESTREAM datawhen accessing through I/O streaming.123