IsolationLevel Enumeration (System.Data)

IsolationLevel Enumeration

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Microsoft Visual Studio 11/.NET Framework 4.5

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.NET Framework Class Library

IsolationLevel Enumeration

[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]

Specifies the transaction locking behavior for the connection.

Namespace: System.Data
Assembly: System.Data (in System.Data.dll)

Syntax

Visual Basic

Public Enumeration IsolationLevel

public enum IsolationLevel

Visual C++

public enum class IsolationLevel

type IsolationLevel

Members

	Member name	Description
	Unspecified	A different isolation level than the one specified is being used, but the level cannot be determined. When using OdbcTransaction, if you do not set IsolationLevel or you set IsolationLevel to Unspecified, the transaction executes according to the isolation level that is determined by the driver that is being used.
	Chaos	The pending changes from more highly isolated transactions cannot be overwritten.
	ReadUncommitted	A dirty read is possible, meaning that no shared locks are issued and no exclusive locks are honored.
	ReadCommitted	Shared locks are held while the data is being read to avoid dirty reads, but the data can be changed before the end of the transaction, resulting in non-repeatable reads or phantom data.
	RepeatableRead	Locks are placed on all data that is used in a query, preventing other users from updating the data. Prevents non-repeatable reads but phantom rows are still possible.
	Serializable	A range lock is placed on the DataSet, preventing other users from updating or inserting rows into the dataset until the transaction is complete.
	Snapshot	Reduces blocking by storing a version of data that one application can read while another is modifying the same data. Indicates that from one transaction you cannot see changes made in other transactions, even if you requery.

Remarks

The IsolationLevel values are used by a .NET Framework data provider when performing a transaction.

The IsolationLevel remains in effect until explicitly changed, but it can be changed at any time. The new value is used at execution time, not parse time. If changed during a transaction, the expected behavior of the server is to apply the new locking level to all statements remaining.

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

Windows 8 Release Preview, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 SP2, Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

System.Data Namespace