select top 5 peopleName,peopleSalary, peopleSex from people where peopleSex ='男'order by peopleSalary desc select top 5 peopleName,peopleSalary, peopleSex from people where peopleSex='女' order...

文章 2017-11-27 来自：开发者社区

SQL查询语句优化的实用方法

查询语句的优化是SQL效率优化的一个方式，可以通过优化sql语句来尽量使用已有的索引，避免全表扫描，从而提高查询效率。最近在对项目中的一些sql进行优化，总结整理了一些方法。 1、在表中建立索引，优先考虑where、group by使用到的字段。 2、尽量避免使用select *，返回无用的字段会降低查询效率。如下： SELECT * FROM t 优化方式：使用具体的字...

文章 2017-02-19 来自：开发者社区

一次SQL查询语句的优化

1.项目中之前的"我关注的拍品列表"需要添加筛选功能，因为目前显示的关注的拍品太多没有进行分类，用户体验差。       2.添加筛选条件之后，可以筛选出“未开始”“进行中”“已结束”三种情况的拍品。    其中              “未开始”--->状态为 &nbs...

问答 2016-06-16 来自：开发者社区

sql查询语句优化

其中t_monitorroom这个表中有一万多条记录，t_monitorroom_role_authority这个表中是存的角色拥有的t_monitorroom中的权限。查询需要9秒多钟，求高手支招优化。

文章 2016-03-01 来自：开发者社区

sql查询语句的优化，exists与in的更换

自己开发的小站，页面访问查询的速度一直不让人满意，刚好今天有时间，就决定对它优化一下。因为在本地开时发，查询的速度是相当快的，一开始就以为是mysql版本的问题，本地是MariaDB 5.5,服务器上是mysql 5.1, 将服务器上的数据弄到本地导了一份，居然发现一样变慢了，平均查询一个文章要1-2秒，列表超过2秒以上，才几千的数据这么慢肯定是哪里出了问题。一点一点的定位打印日志，最...

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