TransactionIsolationLevel Enumerazione
Importante
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Specifica il valore di TransactionAttribute.
public enum class TransactionIsolationLevel
[System.Serializable]
public enum TransactionIsolationLevel
[<System.Serializable>]
type TransactionIsolationLevel =
Public Enum TransactionIsolationLevel
- Ereditarietà
- Attributi
Any | 0 | Il livello di isolamento del componente è ottenuto dal livello di isolamento del componente chiamante. Nel caso del componente di primo livello, il livello di isolamento utilizzato è Serializable. |
ReadCommitted | 2 | Sebbene durante la lettura dei dati vengano utilizzati blocchi condivisi per impedire la lettura dei dati modificati, è possibile apportare modifiche a tali dati prima della fine della transazione. Si otterranno pertanto letture non ripetibili o dati fantasma. |
ReadUncommitted | 1 | Sono attivati blocchi condivisi e vengono ignorati blocchi esclusivi. |
RepeatableRead | 3 | I blocchi sono posizionati su tutti i dati utilizzati in una query, impedendo l'aggiornamento dei dati da parte di altri utenti. Impedisce le letture non ripetibili, ma è sempre possibile ottenere righe fantasma. |
Serializable | 4 | Impedisce l'aggiornamento o l'inserimento fino a quando la transazione non è completa. |
Nell'esempio di codice seguente viene illustrato l'uso TransactionIsolationLevel del tipo.
#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
Prodotto | Versioni |
---|---|
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
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