Question

我有一张桌子

id = 1
name = 'one'
group = 1

id = 2
name = 'two'
group = 1

id = 3
name = 'three'
group = 2

我必须在一个sql查询中获得所有单身名称，在这种情况下id = 3 和另一个sql所有的名称都是倍数，在这种情况下id = 1和id = 2，因为它们具有相同的组。我想它应该是选择但不确定的选择。

提前致谢。

Answer 1

听起来你想要使用类似的东西：

select id
from yourtable
group by `group`
having count(`group`) = 1

请参阅SQL Fiddle with Demo。

然后，如果要返回所有详细信息，则可以将查询扩展为：

select *
from yourtable t1
where id in (select id
            from yourtable t2
            group by `group`
            having count(`group`) = 1)

请参阅SQL Fiddle with Demo。

如果要返回具有相同组的所有行，则可以使用：

select *
from yourtable t1
where `group` in (select `group`
                  from yourtable t2
                  group by `group`
                  having count(`group`) > 1)

请参阅SQL Fiddle with Demo

然后，如果您想要返回所有内容以及标识它是单个还是多个的标志，那么您可以使用与此类似的内容。您会注意到我添加了一个标志，以显示groups有一行，然后哪些组有多行：

select *, 'single' Total
from yourtable t1
where `group` in (select `group`
                  from yourtable t2
                  group by `group`
                  having count(`group`) = 1)
union all
select *, 'multiple' Total
from yourtable t1
where `group` in (select `group`
                  from yourtable t2
                  group by `group`
                  having count(`group`) > 1)

请参阅SQL Fiddle with Demo

在mysql中获取多行和单行

1 个答案: