Member name

Description

Value

Unspecified

Supported by the .NET Compact Framework.

A different isolation level than the one specified is being used, but the level cannot be determined.

-1

Chaos

Supported by the .NET Compact Framework.

The pending changes from more highly isolated transactions cannot be overwritten.

16

ReadUncommitted

Supported by the .NET Compact Framework.

A dirty read is possible, meaning that no shared locks are issued and no exclusive locks are honored.

256

ReadCommitted

Supported by the .NET Compact Framework.

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.

4096

RepeatableRead

Supported by the .NET Compact Framework.

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.

65536

Serializable

Supported by the .NET Compact Framework.

A range lock is placed on the data set, preventing other users from updating or inserting rows into the dataset until the transaction is complete.

1048576

小注: 无序的孤立等级是不被SQL Server 或 Oracle 支持的, 只有OLEDB 数据提供对象将会作为孤立等级设置事务接受它. 如果试图用SQL Server 或Oracle 设置它,将会得到一个ArgumentException, 指明无效的孤立等级参数.

Sql Server 和 Oracle 和 OLE DB 数据提供对象默认为ReadCommitted 孤立等级. ODBC 数据提供对象默认孤立等级各不相同, 依赖于ＯＤＢＣ的驱动的不同．　如果你考虑ReadCommitted　不是你想要的孤立等级，　你可以使用Transaction.IsolationLevel　属性来　指定不同的等级．　你应该非常慎重考虑修改这些设置，虽然，　执行适当的测试来保证，这些变化不能影响数据的一致性，或其它的并发问题．　如果有数据库管理员，　你应该向他们请教关于特定任务的恰当等级．你也应该查看数据库文档来看你的数据库是如何处理孤立等级和锁的．

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