一个查询既有order by desc 又有LIMIT下的排序如何建立索引一个查询既有order by desc 又有limit 的如何建立索引一个表a没有建立索引也没主键.select * from (select * from a where id ='12345' order by date desc lim
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/19 09:17:50
![一个查询既有order by desc 又有LIMIT下的排序如何建立索引一个查询既有order by desc 又有limit 的如何建立索引一个表a没有建立索引也没主键.select * from (select * from a where id ='12345' order by date desc lim](/uploads/image/z/12320360-8-0.jpg?t=%E4%B8%80%E4%B8%AA%E6%9F%A5%E8%AF%A2%E6%97%A2%E6%9C%89order+by+desc+%E5%8F%88%E6%9C%89LIMIT%E4%B8%8B%E7%9A%84%E6%8E%92%E5%BA%8F%E5%A6%82%E4%BD%95%E5%BB%BA%E7%AB%8B%E7%B4%A2%E5%BC%95%E4%B8%80%E4%B8%AA%E6%9F%A5%E8%AF%A2%E6%97%A2%E6%9C%89order+by+desc+%E5%8F%88%E6%9C%89limit+%E7%9A%84%E5%A6%82%E4%BD%95%E5%BB%BA%E7%AB%8B%E7%B4%A2%E5%BC%95%E4%B8%80%E4%B8%AA%E8%A1%A8a%E6%B2%A1%E6%9C%89%E5%BB%BA%E7%AB%8B%E7%B4%A2%E5%BC%95%E4%B9%9F%E6%B2%A1%E4%B8%BB%E9%94%AE.select+%2A+from+%28select+%2A+from+a+where+id+%3D%2712345%27+order+by+date+desc+lim)
一个查询既有order by desc 又有LIMIT下的排序如何建立索引一个查询既有order by desc 又有limit 的如何建立索引一个表a没有建立索引也没主键.select * from (select * from a where id ='12345' order by date desc lim
一个查询既有order by desc 又有LIMIT下的排序如何建立索引
一个查询既有order by desc 又有limit 的如何建立索引
一个表a没有建立索引也没主键.
select * from (select * from a where id ='12345' order by date desc limit 10) a order by date;
请问这句怎么建索引,嗯表a差不多100万行
select * from (select * from a where id ='12345' order by date desc limit 30) a order by date; ----- a差不多100万行,为innodb类型
且id 不唯一;建立复合键时,外层的select 不走索引.我想要的是外层也走索引的建议,
一个查询既有order by desc 又有LIMIT下的排序如何建立索引一个查询既有order by desc 又有limit 的如何建立索引一个表a没有建立索引也没主键.select * from (select * from a where id ='12345' order by date desc lim
如果表只有逆序排序的话,可以建一个逆序索引,在DATE列上,至于ID上的主键当然应该有了,如果它确实是主键的话.外层排序很快,因为只有10条结果,不需要过多考虑.