Question

我有一张带有一些遗留数据的表格,我怀疑这种数据可能微不足道。它是一大批人。

LIST_MEMBERSHIPS
----------------
list_id
address_id

我愿回答一个问题,即每个<代码>的出现情况:<>id>/code>-address_id。

我知道,它涉及<条码>(COUNT)()和<条码>按列出的流放。

Answer 1

select list_id, address_id, count(*) as count
from LIST_MEMBERSHIPS
group by 1, 2
order by 3 desc

您可能认为,添加内容是有益的。

having count > 1

Answer 2

select count(*), list_id, address_id
from list_membership
group by list_id, address_id
order by count(*) desc