GET_FILESTREAM_TRANSACTION_CONTEXT (Transact-SQL)
Zwraca token, który reprezentuje bieżący kontekst transakcji sesja.Token jest używany przez aplikację do powiązania operacje przesyłania strumieniowego systemu plików FILESTREAM transakcji.Aby uzyskać listę tematów FILESTREAM zobacz Projektowanie i wdrażanie FILESTREAM magazynu.
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Składnia
GET_FILESTREAM_TRANSACTION_CONTEXT ()
Zwracany typ
varbinary(max)
Wartość zwracana
Jeśli transakcja nie została uruchomiona, lub został anulowany lub zatwierdzone, zostanie zwrócona wartość NULL.
Uwagi
Transakcja musi być jawne.Użyć instrukcji BEGIN TRANSACTION po zatwierdzeniu transakcji albo TRANSAKCJĘ ROLLBACK.
Podczas wywoływania GET_FILESTREAM_TRANSACTION_CONTEXT wywołujący uzyskuje dostęp do systemu plików do transakcji na czas trwania transakcji.Aby umożliwić innym dostęp użytkownika do transakcji za pośrednictwem systemu plików, umożliwia wykonywanie AS Uruchom jako inny użytkownik GET_FILESTREAM_TRANSACTION_CONTEXT.
Przykłady
W poniższym przykładzie użyto GET_FILESTREAM_TRANSACTION_CONTEXT w Transact-SQL transakcji uzyskać kontekstu transakcji.
using System;
using System.Data.SqlClient;
using System.Data;
namespace ConsoleApplication
{
/// <summary>
/// This class is a wrapper that contains methods for:
///
/// GetTransactionContect() - Returns the current transaction context.
/// BeginTransaction() - Begins a transaction.
/// CommmitTransaction() - Commits the current transaction.
///
/// </summary>
class SqlAccessWrapper
{
/// <summary>
/// Returns a byte array that contains the current transaction
/// context.
/// </summary>
/// <param name="sqlConnection">
/// SqlConnection object that represents the instance of SQL Server
/// from which to obtain the transaction context.
/// </param>
/// <returns>
/// If there is a current transaction context, the return
/// value is an Object that represents the context.
/// If there is not a current transaction context, the
/// value returned is DBNull.Value.
/// </returns>
public Object GetTransactionContext(SqlConnection sqlConnection)
{
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()";
cmd.CommandType = CommandType.Text;
cmd.Connection = sqlConnection;
return cmd.ExecuteScalar();
}
/// <summary>
/// Begins the transaction.
/// </summary>
/// <param name="sqlConnection">
/// SqlConnection object that represents the server
/// on which to run the BEGIN TRANSACTION statement.
/// </param>
public void BeginTransaction(SqlConnection sqlConnection)
{
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "BEGIN TRANSACTION";
cmd.CommandType = CommandType.Text;
cmd.Connection = sqlConnection;
cmd.ExecuteNonQuery();
}
/// <summary>
/// Commits the transaction.
/// </summary>
/// <param name="sqlConnection">
/// SqlConnection object that represents the instance of SQL Server
/// on which to run the COMMIT statement.
/// </param>
public void CommitTransaction(SqlConnection sqlConnection)
{
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "COMMIT TRANSACTION";
cmd.CommandType = CommandType.Text;
cmd.Connection = sqlConnection;
cmd.ExecuteNonQuery();
}
}
class Program
{
static void Main(string[] args)
{
//Open a connection to the local instance of SQL Server.
SqlConnection sqlConnection = new SqlConnection("Integrated Security=true;server=(local)");
sqlConnection.Open();
SqlAccessWrapper sql = new SqlAccessWrapper();
//Create a transaction so that sql.GetTransactionContext() will succeed.
sql.BeginTransaction(sqlConnection);
//The transaction context will be stored in this array.
Byte[] transactionToken;
Object txObj = sql.GetTransactionContext(sqlConnection);
if (DBNull.Value != txObj)
{
transactionToken = (byte[])txObj;
Console.WriteLine("Transaction context obtained.\n");
}
sql.CommitTransaction(sqlConnection);
}
}
}
Imports System
Imports System.Data.SqlClient
Imports System.Data
Namespace ConsoleApplication
''' <summary>
''' This class is a wrapper that contains methods for:
'''
''' GetTransactionContect() - Returns the current transaction context.
''' BeginTransaction() - Begins a transaction.
''' CommmitTransaction() - Commits the current transaction.
'''
''' </summary>
Class SqlAccessWrapper
''' <summary>
''' Returns a byte array that contains the current transaction
''' context.
''' </summary>
''' <param name="sqlConnection">
''' SqlConnection object that represents the instance of SQL Server
''' from which to obtain the transaction context.
''' </param>
''' <returns>
''' If there is a current transaction context, the return
''' value is an Object that represents the context.
''' If there is not a current transaction context, the
''' value returned is DBNull.Value.
''' </returns>
Public Function GetTransactionContext(ByVal sqlConnection As SqlConnection) As Object
Dim cmd As New SqlCommand()
cmd.CommandText = "SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()"
cmd.CommandType = CommandType.Text
cmd.Connection = sqlConnection
Return cmd.ExecuteScalar()
End Function
''' <summary>
''' Begins the transaction.
''' </summary>
''' <param name="sqlConnection">
''' SqlConnection object that represents the server
''' on which to run the BEGIN TRANSACTION statement.
''' </param>
Public Sub BeginTransaction(ByVal sqlConnection As SqlConnection)
Dim cmd As New SqlCommand()
cmd.CommandText = "BEGIN TRANSACTION"
cmd.CommandType = CommandType.Text
cmd.Connection = sqlConnection
cmd.ExecuteNonQuery()
End Sub
''' <summary>
''' Commits the transaction.
''' </summary>
''' <param name="sqlConnection">
''' SqlConnection object that represents the instance of SQL Server
''' on which to run the COMMIT statement.
''' </param>
Public Sub CommitTransaction(ByVal sqlConnection As SqlConnection)
Dim cmd As New SqlCommand()
cmd.CommandText = "COMMIT TRANSACTION"
cmd.CommandType = CommandType.Text
cmd.Connection = sqlConnection
cmd.ExecuteNonQuery()
End Sub
End Class
Class Program
Shared Sub Main()
'''Open a connection to the local instance of SQL Server.
Dim sqlConnection As New SqlConnection("Integrated Security=true;server=(local)")
sqlConnection.Open()
Dim sql As New SqlAccessWrapper()
'''Create a transaction so that sql.GetTransactionContext() will succeed.
sql.BeginTransaction(sqlConnection)
'''The transaction context will be stored in this array.
Dim transactionToken As Byte()
Dim txObj As Object = sql.GetTransactionContext(sqlConnection)
'''If the returned object is not NULL, there is a valid transaction
'''token, and it must be converted into a format that is usable within
'''the application.
If Not txObj.Equals(DBNull.Value) Then
transactionToken = DirectCast(txObj, Byte())
Console.WriteLine("Transaction context obtained." & Chr(10) & "")
End If
sql.CommitTransaction(sqlConnection)
End Sub
End Class
End Namespace
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