如何在SQL中使用同一列两次获取不同的id

我有以下问题。我有一个

user\u id

列和一个

attribute\u id

列，我想获取具有

attribute\u id

1和4的用户id

在这种情况下，结果将是一个单独的列，其中包含

用户id

1和35，一旦它们都具有

属性id

1和4。

您可以使用：

SELECT user_id 
FROM table_name
WHERE attribute_id IN (1, 4)
GROUP BY user_id 
HAVING COUNT(DISTINCT attribute_id) = 2;

with users as
(
select '62' as userid,  1 as attributeid union
select '63' as userid,  1 as attributeid union
select '63' as userid,  1 as attributeid union
select '1' as userid,  1 as attributeid union
select '35' as userid,  1 as attributeid union
select '35' as userid,  4 as attributeid union
select '1' as userid,  4 as attributeid
)
select u1.userid from users u1
    inner join users u4 on u1.userid = u4.userid
                        and u1.attributeid = 1 
                        and u4.attributeid = 4;

---

这取决于您的数据，但如果您只有1和4，您可以这样做：

with users as
(
select '62' as userid,  1 as attributeid union
select '63' as userid,  1 as attributeid union
select '63' as userid,  1 as attributeid union
select '1' as userid,  1 as attributeid union
select '35' as userid,  1 as attributeid union
select '35' as userid,  4 as attributeid union
select '1' as userid,  4 as attributeid
)
select userid from users group by userid having sum(distinct attributeid) = 5;

如果还可以将2和3作为attributeid（因此也可以得到5），则可以使用以下方法：

SELECT user_id 
FROM table_name
WHERE attribute_id IN (1, 4)
GROUP BY user_id 
HAVING COUNT(DISTINCT attribute_id) = 2;

with users as
(
select '62' as userid,  1 as attributeid union
select '63' as userid,  1 as attributeid union
select '63' as userid,  1 as attributeid union
select '1' as userid,  1 as attributeid union
select '35' as userid,  1 as attributeid union
select '35' as userid,  4 as attributeid union
select '1' as userid,  4 as attributeid
)
select u1.userid from users u1
    inner join users u4 on u1.userid = u4.userid
                        and u1.attributeid = 1 
                        and u4.attributeid = 4;

---

这是可行的，但我试图理解为什么，但仍然不确定。你能澄清一下这个查询中发生了什么吗？在

的WHERE

中，查询查找所有用户都有属性_id 1和4，以获得结果X。在

组中，按。。。。如果一个
用户id
有重复的
属性id
，它会在X中计算不同的
属性id
。若表有约束，以确保每个
用户id
都不会重复
属性id
，那个么您可以在查询中省略
DISTINCT
。这里的大多数人想要格式化的文本，而不是图像。