Question

我想知道如果不重复4次，显示所有id_product的正确方法是什么。这是我的表：

id_product  id_related
    55          1
    55          2
    55          3
    55          4
    11          1
    11         123
    11          12
    36          12
    36          9
    36          14
    36          654

我需要找到没有添加4个相关产品的产品。在这种情况下，我期望的结果是11。

Answer 1

这样的事情

select id_product, count(*)
from <table>
group by id_product
having count(*) < 4

Answer 2

以下查询

SELECT id_product
FROM table
GROUP BY id_product
HAVING COUNT(id_product) < 4

Answer 3

Select 
p.id_product,
p.id_related
from product p
join
(
  select 
  id_product,
  count(id_related) as tot
  from product
  group by id_product
  having tot <> 4
)p1
on p1.id_product = p2.id_product

如果你想过滤掉重复的id_related意味着多次出现相同的id_related被计算为一个你可以使用distinct as

count(distinct id_related)

MySQL：如果没有重复4次，请选择id

3 个答案: