TransactionIsolationLevel TransactionIsolationLevel TransactionIsolationLevel TransactionIsolationLevel Enum

Определение

Указывает значение объекта TransactionAttribute.Specifies the value of the TransactionAttribute.

public enum class TransactionIsolationLevel
[System.Serializable]
public enum TransactionIsolationLevel
type TransactionIsolationLevel = 
Public Enum TransactionIsolationLevel
Наследование
TransactionIsolationLevelTransactionIsolationLevelTransactionIsolationLevelTransactionIsolationLevel
Атрибуты

Поля

Any Any Any Any 0

Уровень изоляции для компонента получается из уровня изоляции вызываемого компонента.The isolation level for the component is obtained from the calling component's isolation level. Если это корневой компонент, используется уровень изоляции Serializable.If this is the root component, the isolation level used is Serializable.

ReadCommitted ReadCommitted ReadCommitted ReadCommitted 2

В процессе чтения данных совмещаемые блокировки сохраняются, чтобы избежать чтения измененных данных, однако данные могут быть изменены до окончания транзакции, что может стать причиной неповторяемых считываний или появления фиктивных данных.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

Возникают совмещаемые блокировки и монопольные блокировки не выполняются.Shared locks are issued and no exclusive locks are honored.

RepeatableRead RepeatableRead RepeatableRead RepeatableRead 3

Блокировки помещаются на все данные, используемые в запросе, что предотвращает обновление данных другими пользователями.Locks are placed on all data that is used in a query, preventing other users from updating the data. Предотвращает неповторяемое чтение, однако появление фиктивных строк остается возможным.Prevents non-repeatable reads, but phantom rows are still possible.

Serializable Serializable Serializable Serializable 4

Запрещает обновление или вставку до завершения транзакции.Prevents updating or inserting until the transaction is complete.

Примеры

В следующем примере кода демонстрируется использование TransactionIsolationLevel типа.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
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 'TransactionAttribute_IsolationAny

' 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 'TransactionAttribute_IsolationReadCommitted

' 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 'TransactionAttribute_IsolationReadUncommitted

' 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 'TransactionAttribute_IsolationRepeatableRead

' 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 'TransactionAttribute_IsolationSerializable

Применяется к