顺序
写法顺序:select--from--where--group by--having--order by
执行顺序:from--where--group by--having--select--order by
就是select要放后面,如果有order by,则order by放最后,因为order by 是对结果进行排序
in和exists
- in会先降内表结果缓存起来再做检查
- 当内表数据大时,适合exists,in则反之
Vapriest 2020-05-31 16:06 原文
写法顺序:select--from--where--group by--having--order by
执行顺序:from--where--group by--having--select--order by
就是select要放后面,如果有order by,则order by放最后,因为order by 是对结果进行排序