The database engine acquires shared locks as data is read and releases those locks when the read operation is completed , regardless of the setting of the read committed snapshot database option 无论read _ committed _ snapshot数据库选项的设置如何,数据库引擎都将在读取数据时获取共享锁,在读操作完成后释放这些锁。
If read committed snapshot is set to off the default , the database engine uses shared locks to prevent other transactions from modifying rows while the current transaction is running a read operation 如果将read _ committed _ snapshot设置为off (默认设置) ,则数据库引擎会使用共享锁防止其他事务在当前事务执行读取操作期间修改行。
The microsoft sql server 2005 database engine introduces a new implementation of an existing transaction isolation level , read committed , that provides a statement level snapshot using row versioning Microsoft sql server 2005数据库引擎引入了现有事务隔离级别的一种新的实现方式已提交读,用于提供使用行版本控制的语句级快照。
If the two transactions update rows using a single update statement and do not base the update on the previously retrieved values , lost updates cannot occur at the default isolation level of read committed 如果两个事务使用单个update语句更新行,并且没有按照以前的检索值进行更新,则在设置为提交读的默认隔离级别时,不会发生更新丢失。
If read committed snapshot is set to on , the database engine uses row versioning to present each statement with a transactionally consistent snapshot of the data as it existed at the start of the statement 如果将read _ committed _ snapshot设置为on ,则数据库引擎会使用行版本控制为每个语句提供一个在事务上一致的数据快照,因为该数据在语句开始时就存在。