"SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()" SqlTransaction transaction = sqlConnection.BeginTransaction("mainTranaction") management, such as the SqlTransaction class. should use appropriate API facilities for transaction management, which the Transact-SQL BEGIN TRANSACTION statement have specific rules for batch scoped transactions, All SQL FILESTREAM BLOB access must occur in
The next task is to obtain a transaction Object pathObj = sqlCommand.ExecuteScalar() of the SQL FILESTREAM BLOB that we want to The first task is to retrieve the file path SqlCommand sqlCommand = new SqlCommand() "Integrated Security=true server=(local)") SqlConnection sqlConnection = new SqlConnection(
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The following examples show you how to obtain a Win32 File handle and use it to read and write data to a FILESTREAM BLOB. The returned handle can be passed to any of the following Win32 APIs: ReadFile, WriteFile, TransmitFile, SetFilePointer, SetEndOfFile, or FlushFileBuffers. This API is exported from the sqlncli.dll file. To obtain a Win32 file handle, call the OpenSqlFilestream API. SELECT = GET_FILESTREAM_TRANSACTION_CONTEXT() The following example shows how to begin a transaction and read the current transaction context. To obtain the current transaction context, use the Transact-SQL GET_FILESTREAM_TRANSACTION_CONTEXT() function. The following example shows how to read the file path of a varbinary(max) column. To read the path, use the PathName property of a varbinary(max) column in a Transact-SQL statement. Steps for Accessing FILESTREAM Data Reading the FILESTREAM File PathĮach cell in a FILESTREAM table has a file path that is associated with it. Transact-SQL statements can be executed in the same transaction to maintain consistency between SQL data and FILESTREAM data. The application should close the handle by using CloseHandle.Īll FILESTREAM data container access is performed in a SQL Server transaction. If the application calls any other API by using the handle, an ERROR_ACCESS_DENIED error is returned. The application uses the handle to stream the FILESTREAM data, and can then pass the handle to the following Win32 APIs: ReadFile, WriteFile, TransmitFile, SetFilePointer, SetEndOfFile, or FlushFileBuffers. The OpenSqlFilestream API obtains a Win32 file handle. An application uses this token to bind FILESTREAM file system streaming operations to the transaction. GET_FILESTREAM_TRANSACTION_CONTEXT() returns a token that represents the current transaction of a session. When the database that contains FILESTREAM data belongs to an Always On availability group, then the PathName function returns a virtual network name (VNN) instead of a computer name. An application uses this token to obtain a Win32 handle and operate on BLOB data. PathName returns a path as a token to a BLOB. To support working with FILESTREAM BLOB data in Win32 applications, SQL Server provides the following functions and API: When you use FILESTREAM to store binary large object (BLOB) data, you can use Win32 APIs to work with the files.
Functions for Working with FILESTREAM Data The examples in this topic require the FILESTREAM-enabled database and table that are created in Create a FILESTREAM-Enabled Database and Create a Table for Storing FILESTREAM Data.