数据库SQL优化的相关内容

文章 2017-12-27 来自：开发者社区

数据库的SQL优化

1.对查询进行优化，要尽量避免全表扫描，首先应考虑在 where 及 order by 涉及的列上建立索引。（因为在条件查询条件添加索引，会直接被检索到列，会非常的快速） 2.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（最好不要给数据库留NULL，尽可能的使用 NOT NULL填充数据库.）例如： ...

问答 2016-06-14 来自：开发者社区

求数据库大神帮忙，SQL优化

小弟数据库方面的知识非常浅薄，只会写sql语句实现查询，但是确不会做优化，以下有两个sql语句，在数据库中执行的非常慢，DB2，有没有数据库大神，帮忙优化一下，不胜感激。

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