---
title: "Supporting Local Transactions | Microsoft Docs"
ms.custom: ""
ms.date: "03/14/2017"
ms.prod: sql
ms.prod_service: "database-engine, sql-database, sql-data-warehouse, pdw"
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ms.technology: native-client
ms.topic: "reference"
helpviewer_keywords: 
  - "OLE DB, transactions"
  - "autocommit mode"
  - "transactions [OLE DB]"
  - "ITransactionLocal interface"
  - "SQL Server Native Client OLE DB provider, transactions"
  - "local transactions [OLE DB]"
ms.assetid: 78f2e5fc-b6fb-4eda-9f71-991a4d6c4902
author: markingmyname
ms.author: maghan
monikerRange: ">=aps-pdw-2016||=azuresqldb-current||=azure-sqldw-latest||>=sql-server-2016||=sqlallproducts-allversions||>=sql-server-linux-2017||=azuresqldb-mi-current"
---
# Supporting Local Transactions
[!INCLUDE[appliesto-ss-asdb-asdw-pdw-md](../../includes/appliesto-ss-asdb-asdw-pdw-md.md)]

  A session delimits transaction scope for a [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider local transaction. When, at the direction of a consumer, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider submits a request to a connected instance of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)], the request constitutes a unit of work for the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider. Local transactions always wrap one or more units of work on a single [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider session.  
  
 Using the default [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider autocommit mode, a single unit of work is treated as the scope of a local transaction. Only one unit participates in the local transaction. When a session is created, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider begins a transaction for the session. Upon successful completion of a work unit, the work is committed. On failure, any work begun is rolled back and the error is reported to the consumer. In either case, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider begins a new local transaction for the session so that all work is conducted within a transaction.  
  
 The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider consumer can direct more precise control over local transaction scope by using the **ITransactionLocal** interface. When a consumer session initiates a transaction, all session work units between the transaction start point and the eventual **Commit** or **Abort** method calls are treated as an atomic unit. The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider implicitly begins a transaction when directed to do so by the consumer. If the consumer does not request retention, the session reverts to parent transaction-level behavior, most commonly autocommit mode.  
  
 The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider supports **ITransactionLocal::StartTransaction** parameters as follows.  
  
|Parameter|Description|  
|---------------|-----------------|  
|*isoLevel*[in]|The isolation level to be used with this transaction. In local transactions, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider supports the following:<br /><br /> **ISOLATIONLEVEL_UNSPECIFIED**<br /><br /> **ISOLATIONLEVEL_CHAOS**<br /><br /> **ISOLATIONLEVEL_READUNCOMMITTED**<br /><br /> **ISOLATIONLEVEL_READCOMMITTED**<br /><br /> **ISOLATIONLEVEL_REPEATABLEREAD**<br /><br /> **ISOLATIONLEVEL_CURSORSTABILITY**<br /><br /> **ISOLATIONLEVEL_REPEATABLEREAD**<br /><br /> **ISOLATIONLEVEL_SERIALIZABLE**<br /><br /> **ISOLATIONLEVEL_ISOLATED**<br /><br /> **ISOLATIONLEVEL_SNAPSHOT**<br /><br /> <br /><br /> Note: Beginning with [!INCLUDE[ssVersion2005](../../includes/ssversion2005-md.md)], ISOLATIONLEVEL_SNAPSHOT is valid for the *isoLevel* argument whether or not versioning is enabled for the database. However, an error will occur if the user attempts to execute a statement and versioning is not enabled and/or the database is not read-only. In addition, the error XACT_E_ISOLATIONLEVEL will occur if ISOLATIONLEVEL_SNAPSHOT is specified as the *isoLevel* when connected to a version of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] earlier than [!INCLUDE[ssVersion2005](../../includes/ssversion2005-md.md)].|  
|*isoFlags*[in]|The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider returns an error for any value other than zero.|  
|*pOtherOptions*[in]|If not NULL, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider requests the options object from the interface. The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider returns XACT_E_NOTIMEOUT if the options object's *ulTimeout* member is not zero. The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider ignores the value of the *szDescription* member.|  
|*pulTransactionLevel*[out]|If not NULL, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider returns the nested level of the transaction.|  
  
 For local transactions, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider implements **ITransaction::Abort** parameters as follows.  
  
|Parameter|Description|  
|---------------|-----------------|  
|*pboidReason*[in]|Ignored if set. Can safely be NULL.|  
|*fRetaining*[in]|When TRUE, a new transaction is implicitly begun for the session. The transaction must be committed or terminated by the consumer. When FALSE, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider reverts to autocommit mode for the session.|  
|*fAsync*[in]|Asynchronous abort is not supported by the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider. The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider returns XACT_E_NOTSUPPORTED if the value is not FALSE.|  
  
 For local transactions, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider implements **ITransaction::Commit** parameters as follows.  
  
|Parameter|Description|  
|---------------|-----------------|  
|*fRetaining*[in]|When TRUE, a new transaction is implicitly begun for the session. The transaction must be committed or terminated by the consumer. When FALSE, the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider reverts to autocommit mode for the session.|  
|*grfTC*[in]|Asynchronous and phase one returns are not supported by the [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider. The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider returns XACT_E_NOTSUPPORTED for any value other than XACTTC_SYNC.|  
|*grfRM*[in]|Must be 0.|  
  
 The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider rowsets on the session are preserved on a local commit or abort operation based on the values of the rowset properties DBPROP_ABORTPRESERVE and DBPROP_COMMITPRESERVE. By default, these properties are both VARIANT_FALSE and all [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider rowsets on the session are lost following an abort or commit operation.  
  
 The [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client OLE DB provider does not implement the **ITransactionObject** interface. A consumer attempt to retrieve a reference on the interface returns E_NOINTERFACE.  
  
 This example uses **ITransactionLocal**.  
  
```  
// Interfaces used in the example.  
IDBCreateSession*   pIDBCreateSession   = NULL;  
ITransaction*       pITransaction       = NULL;  
IDBCreateCommand*   pIDBCreateCommand   = NULL;  
IRowset*            pIRowset            = NULL;  
  
HRESULT             hr;  
  
// Get the command creation and local transaction interfaces for the  
// session.  
if (FAILED(hr = pIDBCreateSession->CreateSession(NULL,  
     IID_IDBCreateCommand, (IUnknown**) &pIDBCreateCommand)))  
    {  
    // Process error from session creation. Release any references and  
    // return.  
    }  
  
if (FAILED(hr = pIDBCreateCommand->QueryInterface(IID_ITransactionLocal,  
    (void**) &pITransaction)))  
    {  
    // Process error. Release any references and return.  
    }  
  
// Start the local transaction.  
if (FAILED(hr = ((ITransactionLocal*) pITransaction)->StartTransaction(  
    ISOLATIONLEVEL_REPEATABLEREAD, 0, NULL, NULL)))  
    {  
    // Process error from StartTransaction. Release any references and  
    // return.  
    }  
  
// Get data into a rowset, then update the data. Functions are not  
// illustrated in this example.  
if (FAILED(hr = ExecuteCommand(pIDBCreateCommand, &pIRowset)))  
    {  
    // Release any references and return.  
    }  
  
// If rowset data update fails, then terminate the transaction, else  
// commit. The example doesn't retain the rowset.  
if (FAILED(hr = UpdateDataInRowset(pIRowset, bDelayedUpdate)))  
    {  
    // Get error from update, then terminate.  
    pITransaction->Abort(NULL, FALSE, FALSE);  
    }  
else  
    {  
    if (FAILED(hr = pITransaction->Commit(FALSE, XACTTC_SYNC, 0)))  
        {  
        // Get error from failed commit.  
        }  
    }  
  
if (FAILED(hr))  
    {  
    // Update of data or commit failed. Release any references and  
    // return.  
    }  
  
// Release any references and continue.  
```  
  
## See Also  
 [Transactions](../../relational-databases/native-client-ole-db-transactions/transactions.md)   
 [Working with Snapshot Isolation](../../relational-databases/native-client/features/working-with-snapshot-isolation.md)