如何計算MySQL中值的非唯一組合？

Question

我有一個表，其中包含一些舊數據，我懷疑這些舊數據可能有些混亂。 這是一個多對多聯接表。

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

我想運行一個查詢，該查詢將計算每個list_id - address_id對的出現次數，並顯示從最高到最低出現次數中的每一個的出現次數。

我知道必須涉及COUNT()和GROUP BY ，對嗎？

Answer 1

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

您可能會發現添加有用

having count > 1

Answer 2

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