在mysql中獲取多行和單行

Question

我有一張桌子

id = 1
name = 'one'
group = 1

id = 2
name = 'two'
group = 1

id = 3
name = 'three'
group = 2

並且我必須在一個sql查詢中獲得所有單個名稱，在這種情況下id = 3和另一個sql所有名稱都是倍數，在這種情況下id = 1和id = 2，因為它們具有相同的組。 我想它應該是選擇但不確定的選擇。

提前致謝。

Answer 1

聽起來你想要使用類似的東西：

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

請參閱SQL Fiddle with Demo 。

然后，如果要返回所有詳細信息，則可以將查詢擴展為：

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

請參閱SQL Fiddle with Demo 。

如果要返回具有相同組的所有行，則可以使用：

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

請參閱SQL Fiddle with Demo

然后，如果您想要返回所有內容以及標識它是單個還是多個的標志，那么您可以使用與此類似的內容。 您會注意到我包含一個標志，以顯示哪些groups有一行，然后哪些組有多行：

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)

請參閱SQL Fiddle with Demo