TransactionIsolationLevel Enum
Definition
Viktigt
En del information gäller för förhandsversionen av en produkt och kan komma att ändras avsevärt innan produkten blir allmänt tillgänglig. Microsoft lämnar inga garantier, uttryckliga eller underförstådda, avseende informationen som visas här.
Anger värdet för TransactionAttribute.
public enum class TransactionIsolationLevel[System.Serializable]
public enum TransactionIsolationLevel[<System.Serializable>]
type TransactionIsolationLevel = Public Enum TransactionIsolationLevel- Arv
- Attribut
Fält
| Name | Värde | Description |
|---|---|---|
| Any | 0 | Isoleringsnivån för komponenten hämtas från den anropande komponentens isoleringsnivå. Om det här är rotkomponenten är Serializableden isoleringsnivå som används . |
| ReadUncommitted | 1 | Delade lås utfärdas och inga exklusiva lås respekteras. |
| ReadCommitted | 2 | Delade lås lagras medan data läss för att undvika att läsa ändrade data, men data kan ändras före transaktionens slut, vilket resulterar i icke-repeterbara läsningar eller fiktiva data. |
| RepeatableRead | 3 | Lås placeras på alla data som används i en fråga, vilket hindrar andra användare från att uppdatera data. Förhindrar icke-repeterbara läsningar, men fiktiva rader är fortfarande möjliga. |
| Serializable | 4 | Förhindrar uppdatering eller infogning tills transaktionen har slutförts. |
Exempel
I följande kodexempel visas användningen av TransactionIsolationLevel typen.
#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