MDAC 2.5 SDK - OLE DB Providers
OLE DB Provider for SQL Server

Transactions

SQLOLEDB implements local transaction support. The consumer can use distributed or coordinated transactions by using Microsoft® Distributed Transaction Coordinator (MS DTC). For consumers requiring transaction control that spans multiple sessions, SQLOLEDB can join transactions initiated and maintained by MS DTC.

By default, SQLOLEDB uses an auto-commit transaction mode, where each discrete action on a consumer session comprises a complete transaction against a Microsoft SQL Server™ installation. SQLOLEDB auto-commit mode is local, and auto-commit transactions never span more than a single session.

SQLOLEDB exposes the ITransactionLocal interface, allowing the consumer to use explicitly and implicitly started transactions on a single SQL Server connection. SQLOLEDB does not support nested local transactions.