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sqlserver nolock

时间: 2023-11-10 15:46:11 浏览: 125

SQL Server的WITH (NOLOCK)

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缺点: 　　1.会产生脏读　　2.只适用与select查询语句　　优点: 　　1.有些文件说，加了WITH (NOLOCK)的SQL查询效率可以增加33%。　　2.可以用于inner join 语句　　脏读: 一个用户对一个资源做了修改，此时另外一个用户正好读取了这条被修改的记录，然后，第一个用户放弃修改，数据回到修改之前，这两个不同的结果是脏读。　　详细内容: 　　要提升SQL的查询效能，一般来说大家会以建立索引(index)为第一考虑。其实除了index的建立之外，当我们在下SQL Command时，在语法中加一段WITH (NOLOCK)可以改善在线大量查询的环

SQL Server NOLOCK is a locking hint that can be used to specify that a query should be able to read data from tables that are currently being modified by other transactions. It allows read operations to proceed without waiting for the locks to be released by the modifying transactions, which can improve performance in certain situations. However, it may also introduce inconsistencies and data inaccuracies, so it should be used with caution.

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