IsolationLevel IsolationLevel IsolationLevel IsolationLevel Enum


指定事务的隔离级别。Specifies the isolation level of a transaction.

public enum class IsolationLevel
public enum IsolationLevel
type IsolationLevel = 
Public Enum IsolationLevel


Chaos Chaos Chaos Chaos 5

无法覆盖隔离级别更高的事务中的挂起的更改。The pending changes from more highly isolated transactions cannot be overwritten.

ReadCommitted ReadCommitted ReadCommitted ReadCommitted 2

不可以在事务期间读取可变数据,但是可以修改。Volatile data cannot be read during the transaction, but can be modified.

ReadUncommitted ReadUncommitted ReadUncommitted ReadUncommitted 3

可以在事务期间读取和修改可变数据。Volatile data can be read and modified during the transaction.

RepeatableRead RepeatableRead RepeatableRead RepeatableRead 1

可以在事务期间读取可变数据,但是不可以修改。Volatile data can be read but not modified during the transaction. 可以在事务期间添加新数据。New data can be added during the transaction.

Serializable Serializable Serializable Serializable 0

可以在事务期间读取可变数据,但是不可以修改,也不可以添加任何新数据。Volatile data can be read but not modified, and no new data can be added during the transaction.

Snapshot Snapshot Snapshot Snapshot 4

可以读取可变数据。Volatile data can be read. 在事务修改数据之前,它会验证在它最初读取数据之后另一个事务是否更改过这些数据。Before a transaction modifies data, it verifies if another transaction has changed the data after it was initially read. 如果数据已更新,则会引发错误。If the data has been updated, an error is raised. 这样,事务可获取先前提交的数据值。This allows a transaction to get to the previously committed value of the data.

当尝试提升已创建的 Snapshot 隔离级别的事务时,将引发 InvalidOperationException,并显示错误消息“无法提升快照隔离级别的事务”。When you try to promote a transaction that was created with the Snapshot isolation level, an InvalidOperationException is thrown with the error message "Transactions with IsolationLevel Snapshot cannot be promoted".

Unspecified Unspecified Unspecified Unspecified 6

正在使用与指定隔离级别不同的隔离级别,但是无法确定该级别。A different isolation level than the one specified is being used, but the level cannot be determined. 如果设置了此值,则会引发异常。An exception is thrown if this value is set.


受事务影响的数据称为 "可变"。The data affected by a transaction is called volatile. 在创建事务时,可以指定应用于该事务的隔离级别。When you create a transaction, you can specify the isolation level that applies to the transaction. 事务的隔离级别决定了在事务完成之前, 其他事务对可变数据的访问级别。The isolation level of a transaction determines what level of access other transactions have to volatile data before a transaction completes.

最小隔离级别ReadUncommitted允许多个事务同时对数据存储进行操作, 并且不会因会造成中断事务而导致数据损坏。The lowest isolation level, ReadUncommitted, allows many transactions to operate on a data store simultaneously and provides no protection against data corruption due to interruptive transactions. 最高隔离级别Serializable提供对会造成中断事务的高度保护, 但要求在允许任何其他事务对数据执行操作之前完成每个事务。The highest isolation level, Serializable, provides a high degree of protection against interruptive transactions, but requires that each transaction complete before any other transactions are allowed to operate on the data.

事务的隔离级别是在创建事务时确定的。The isolation level of a transaction is determined when the transaction is created. 默认情况下, System.Transactions基础结构Serializable将创建事务。By default, the System.Transactions infrastructure creates Serializable transactions. 您可以通过使用Transaction.IsolationLevel事务的属性来确定现有事务的隔离级别。You can determine the isolation level of an existing transaction by using the Transaction.IsolationLevel property of a transaction.