TransactionIsolationLevel TransactionIsolationLevel TransactionIsolationLevel TransactionIsolationLevel Enum

Definition

Gibt den Wert des TransactionAttribute an.Specifies the value of the TransactionAttribute.

public enum class TransactionIsolationLevel
[System.Serializable]
public enum TransactionIsolationLevel
type TransactionIsolationLevel = 
Public Enum TransactionIsolationLevel
Vererbung
TransactionIsolationLevelTransactionIsolationLevelTransactionIsolationLevelTransactionIsolationLevel
Attribute

Felder

Any Any Any Any 0

Der Isolationsgrad für die Komponente wird aus dem Isolationsgrad der aufrufenden Komponente abgerufen.The isolation level for the component is obtained from the calling component's isolation level. Wenn es sich hierbei um die Stammkomponente handelt, wird als Isolationsgrad Serializable verwendet.If this is the root component, the isolation level used is Serializable.

ReadCommitted ReadCommitted ReadCommitted ReadCommitted 2

Beim Lesen der Daten werden gemeinsame Sperren verwendet, um das Lesen geänderter Daten zu verhindern. Die Daten können jedoch vor dem Ende der Transaktion geändert werden, was zu nicht wiederholbaren Lesevorgängen oder zu Phantomdaten führt.Shared locks are held while the data is being read to avoid reading modified data, but the data can be changed before the end of the transaction, resulting in non-repeatable reads or phantom data.

ReadUncommitted ReadUncommitted ReadUncommitted ReadUncommitted 1

Es werden gemeinsame Sperren ausgegeben und keine exklusiven Sperren beachtet.Shared locks are issued and no exclusive locks are honored.

RepeatableRead RepeatableRead RepeatableRead RepeatableRead 3

Die Sperren gelten für alle in einer Abfrage verwendeten Daten, damit die Daten nicht durch andere Benutzer aktualisiert werden können.Locks are placed on all data that is used in a query, preventing other users from updating the data. Nicht wiederholbare Lesevorgänge werden dadurch verhindert, es sind jedoch weiterhin Phantomzeilen möglich.Prevents non-repeatable reads, but phantom rows are still possible.

Serializable Serializable Serializable Serializable 4

Verhindert das Aktualisieren oder Einfügen, bis die Transaktion abgeschlossen ist.Prevents updating or inserting until the transaction is complete.

Beispiele

Im folgenden Codebeispiel wird die Verwendung des TransactionIsolationLevel -Typs veranschaulicht.The following code example demonstrates the use of the TransactionIsolationLevel type.

#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

Gilt für: