TransactionIsolationLevel Výčet

  • Reference

Definice

Obor názvů:
System.EnterpriseServices
Sestavení:
System.EnterpriseServices.dll

Určuje hodnotu TransactionAttribute.

public enum class TransactionIsolationLevel
[System.Serializable]
public enum TransactionIsolationLevel
[<System.Serializable>]
type TransactionIsolationLevel = 
Public Enum TransactionIsolationLevel
Dědičnost
Object
ValueType
Enum
TransactionIsolationLevel
Atributy
SerializableAttribute

Pole

Any 0

Úroveň izolace pro komponentu se získá z úrovně izolace volající komponenty. Pokud se jedná o kořenovou komponentu, použije se Serializableúroveň izolace .
ReadCommitted 2

Sdílené zámky se zachovají během čtení dat, aby se zabránilo čtení upravených dat, ale data lze před koncem transakce změnit, což vede k neopakovatelným čtením nebo fiktivním datům.
ReadUncommitted 1

Jsou vydány sdílené zámky a nejsou respektovány žádné výhradní zámky.
RepeatableRead 3

Zámky se umisťují na všechna data použitá v dotazu, což ostatním uživatelům brání v aktualizaci dat. Zabraňuje neopakovatelnému čtení, ale fiktivní řádky jsou stále možné.
Serializable 4

Zabrání aktualizaci nebo vložení až do dokončení transakce.

Příklady

Následující příklad kódu ukazuje použití 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

Platí pro