优化SQL查询的相关内容

文章 2022-02-17 来自：开发者社区

浅谈MySQL中优化sql语句查询常用的30种方法

1.对查询进行优化，应尽量避免全表扫描，首先应考虑在 where 及 order by 涉及的列上建立索引。 2.应尽量避免在 where 子句中使用!=或<>操作符，否则将引擎放弃使用索引而进行全表扫描。 3.应尽量避免在 where 子句中对字段进行 null 值判断，否则将导致引擎放弃使用索引而进行全表扫描，如： select id from t ...

文章 2022-02-17 来自：开发者社区

通过手动创建统计信息优化sql查询性能案例

本质原因在于：SQL Server 统计信息只包含复合索引的第一个列的信息，而不包含复合索引数据组合的信息来源于工作中的一个实际问题，这里是组合列数据不均匀导致查询无法预估数据行数，从而导致无法选择合理的执行计划导致性能低下的情况我这里把问题简单化，主要是为了说明问题如下一张业务表，主要看两个“状态”字段，BusinessStatus1 和 BusinessStatus2 c...

文章 2022-02-17 来自：开发者社区

优化SQL Server数据库查询方法

本文详细介绍了优化SQL Server数据库查询方法。　　SQL Server数据库查询速度慢的原因有很多，常见的有以下几种：　　1、没有索引或者没有用到索引（这是查询慢最常见的问题，是程序设计的缺陷）　　2、I/O吞吐量小，形成了瓶颈效应。　　3、没有创建计算列导致查询不优化。　　4、内存不足　　5、网络速度慢　　6、查询出的数据量过大（可以采用多次查询，其他的方法降低数据量） ....

文章 2022-02-16 来自：开发者社区

优化SQL语句查询

这是我写的MYSQL查询语句，这样写是为了一次查询完成，可是现在发现随着数据的增加，用这个查询语句非常耗时，并且加大了mysql的压力，希望大神指点一二！如何优化这个语句，希望还是可以一句查询完成！

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更新时间 2025-03-26 13:33:29

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