Question

我是sql的新手，任何人都可以帮我从内部查询中获取有序数据

select 
    * 
from emp 
where id 
    (select order from department where name = 'testing' order by order asc).

我从内部查询获取订单数据，并且我得到了id，我应该从emp表中获得与内部查询相同的顺序。谁能帮我这个。 TIA。

Answer 1

如果将查询重新编写为连接是合理的：

select e.*
from emp e
inner join department d
    on e.id = d.order
where d.name = 'testing'
order by d.order asc

如果department中有多个行与order中的一行或多行匹配emp，那么这会改变您的结果 - 在这种情况下 this < / em> query将返回多行，而原始则不会。但如果这种情况不适用，那么这就是我建议的查询。

Answer 2

如果emp.id和department.order之间的匹配次数超过1，这将给出正确的行数

select * from emp e
where exists
(select 1 from department d where d.name = 'testing' 
and e.id = d.order1) -- order is a reserved word in several sql languages
order by id

你的桌子之间似乎有些搞笑。部门是否会包含有关emp的任何信息（我假设它是员工表）？

Answer 3

无法保证存在具有内部查询的实际临时表，并且以某种方式对其进行排序和处理。但是，您可以通过emp.id对外部查询进行排序。

select * from emp where id in 
     (select order from department where name = 'testing')
order by id asc

Answer 4

达米恩的回答非常酷和完美。但如果您仍想使用子查询，请尝试使用

select * 
from emp 
where id in (select order from department where name = 'testing' order by order asc) 
order by id asc

这可以帮助你

Answer 5

select e.* from emp as e, department d where e.id=d.order and d.name='testing' order by d.order

如何通过内部查询获取订单

5 个答案: