TransactionIsolationLevel Wyliczenie

Definicja

Przestrzeń nazw:

System.EnterpriseServices

Zestaw:

System.EnterpriseServices.dll

Określa wartość .TransactionAttribute

public enum class TransactionIsolationLevel

[System.Serializable]
public enum TransactionIsolationLevel

[<System.Serializable>]
type TransactionIsolationLevel = 

Public Enum TransactionIsolationLevel

Dziedziczenie

Object

ValueType

Enum

TransactionIsolationLevel

Atrybuty

SerializableAttribute

Pola

Any	0	Poziom izolacji składnika jest uzyskiwany z poziomu izolacji wywołującego składnika. Jeśli jest to składnik główny, używany poziom izolacji to Serializable.
ReadCommitted	2	Blokady udostępnione są przechowywane, gdy dane są odczytywane, aby uniknąć odczytywania zmodyfikowanych danych, ale dane można zmienić przed końcem transakcji, co powoduje nie powtarzalne odczyty lub dane fantomowe.
ReadUncommitted	1	Udostępnione blokady są wydawane i nie są honorowane żadne blokady wyłączne.
RepeatableRead	3	Blokady są umieszczane na wszystkich danych używanych w zapytaniu, co uniemożliwia innym użytkownikom aktualizowanie danych. Zapobiega powtarzalnym odczytom, ale wiersze fantomowe są nadal możliwe.
Serializable	4	Uniemożliwia aktualizowanie lub wstawianie do momentu ukończenia transakcji.

Przykłady

W poniższym przykładzie kodu pokazano użycie TransactionIsolationLevel typu .

#using <System.EnterpriseServices.dll>

using namespace System;
using namespace System::EnterpriseServices;
using namespace System::Reflection;

// References:
// System.EnterpriseServices

// An instance of this class will inherit its caller's transaction isolation
// level if available. If not, it will use isolation level Serializable.
[Transaction(Isolation=TransactionIsolationLevel::Any)]
public ref class IsolationAny : public ServicedComponent
{
};

// An instance of this class will read only committed data, but non-repeatable
// reads and phantom rows are still possible.
[Transaction(Isolation=TransactionIsolationLevel::ReadCommitted)]
public ref class IsolationReadCommitted : public ServicedComponent
{
};

// An instance of this class will read committed and uncommitted data, so dirty
// reads, non-repeatable reads, and phantom rows are possible.
[Transaction(Isolation=TransactionIsolationLevel::ReadUncommitted)]
public ref class IsolationReadUncommitted : public ServicedComponent
{
};

// An instance of this class will read only committed data and place shared
// locks on the data, preventing other users from modifying it, but other users
// can still insert rows into the data set, so phantom rows are still possible.
[Transaction(Isolation=TransactionIsolationLevel::RepeatableRead)]
public ref class IsolationRepeatableRead : public ServicedComponent
{
};

// An instance of this class will read only committed data and place a range
// lock on the data set, preventing other users from updating or inserting rows
// into the data set until its transaction is complete.
[Transaction(Isolation=TransactionIsolationLevel::Serializable)]
public ref class IsolationSerializable : public ServicedComponent
{
};

using System;
using System.EnterpriseServices;
using System.Reflection;

// References:
// System.EnterpriseServices

// An instance of this class will inherit its caller's transaction isolation
// level if available. If not, it will use isolation level Serializable.
[Transaction(Isolation=TransactionIsolationLevel.Any)]
public class TransactionAttribute_IsolationAny : ServicedComponent
{
}

// An instance of this class will read only committed data, but non-repeatable
// reads and phantom rows are still possible.
[Transaction(Isolation=TransactionIsolationLevel.ReadCommitted)]
public class TransactionAttribute_IsolationReadCommitted : ServicedComponent
{
}

// An instance of this class will read committed and uncommitted data, so dirty
// reads, non-repeatable reads, and phantom rows are possible.
[Transaction(Isolation=TransactionIsolationLevel.ReadUncommitted)]
public class TransactionAttribute_IsolationReadUncommitted : ServicedComponent
{
}

// An instance of this class will read only committed data and place shared
// locks on the data, preventing other users from modifying it, but other users
// can still insert rows into the data set, so phantom rows are still possible.
[Transaction(Isolation=TransactionIsolationLevel.RepeatableRead)]
public class TransactionAttribute_IsolationRepeatableRead : ServicedComponent
{
}

// An instance of this class will read only committed data and place a range
// lock on the data set, preventing other users from updating or inserting rows
// into the data set until its transaction is complete.
[Transaction(Isolation=TransactionIsolationLevel.Serializable)]
public class TransactionAttribute_IsolationSerializable : ServicedComponent
{
}

Imports System.EnterpriseServices
Imports System.Reflection


' References:
' System.EnterpriseServices

' An instance of this class will inherit its caller's transaction isolation
' level if available. If not, it will use isolation level Serializable.
<Transaction(Isolation := TransactionIsolationLevel.Any)>  _
Public Class TransactionAttribute_IsolationAny
    Inherits ServicedComponent
End Class

' An instance of this class will read only committed data, but non-repeatable
' reads and phantom rows are still possible.
<Transaction(Isolation := TransactionIsolationLevel.ReadCommitted)>  _
Public Class TransactionAttribute_IsolationReadCommitted
    Inherits ServicedComponent
End Class

' An instance of this class will read committed and uncommitted data, so dirty
' reads, non-repeatable reads, and phantom rows are possible.
<Transaction(Isolation := TransactionIsolationLevel.ReadUncommitted)>  _
Public Class TransactionAttribute_IsolationReadUncommitted
    Inherits ServicedComponent
End Class

' An instance of this class will read only committed data and place shared
' locks on the data, preventing other users from modifying it, but other users
' can still insert rows into the data set, so phantom rows are still possible.
<Transaction(Isolation := TransactionIsolationLevel.RepeatableRead)>  _
Public Class TransactionAttribute_IsolationRepeatableRead
    Inherits ServicedComponent
End Class

' An instance of this class will read only committed data and place a range
' lock on the data set, preventing other users from updating or inserting rows
' into the data set until its transaction is complete.
<Transaction(Isolation := TransactionIsolationLevel.Serializable)>  _
Public Class TransactionAttribute_IsolationSerializable
    Inherits ServicedComponent
End Class