having子句中如何有'distinct'

Question

编辑：这是一个示例关系！我需要它处理更大的关系，所以没有解决方法！

所以我得到了一个简单的任务，起初我没有看到可能有什么问题，现在我只是不明白为什么它不起作用。

假设我有 table 个人和他们的朋友，我想 select 有 2 个或更多朋友的人。

人

------------------------------
|person  | friend | relation |
|-----------------------------
|ana     | jon    | friend   |
|ana     | jon    | lover    |
|ana     | phillip| friend   |
|ana     | kiki   | friend   |
|mary    | jannet | friend   |
|mary    | jannet | lover    |
|peter   | july   | friend   |

我想做一个

 SELECT person FROM people GROUP BY person HAVING count(distinct friend) > 1;

并得到

-------
| ana |
-------

但是在 HAVING 子句中使用“distinct”时出现语法错误。我知道“distinct”是投影子句的一部分，但是如何让“count”只计算不同的条目而不需要额外的子查询或其他东西？

编辑：我能想到的最好的是：

SELECT tmp.person FROM (SELECT person, count(distinct friend) 
             AS numfriends FROM people GROUP BY person) AS tmp 
       WHERE tmp.numfriends > 1;

Answer 1

你需要这样写

SELECT person
FROM people
WHERE relation = 'friend'
GROUP BY person 
HAVING count(*) > 1;

Answer 2

只需检查一下即可。

declare @t table(person varchar(50),  Friend VARCHAR(50), relation VARCHAR(50))

INSERT INTO @T VALUES('ana', 'jon','friend')
,('ana', 'jon','lover')
,('ana', 'phillip','friend')
,('ana', 'kiki','friend')
,('mary', 'jannat','friend')
,('mary', 'jannat','lover')


SELECT DISTINCT PERSON FROM 
(
    SELECT person FROM @t GROUP BY person HAVING count(friend) > 1
) a

Answer 3

来自文档

http://www-01.ibm.com/support/knowledgecenter/SSGU8G_12.1.0/com.ibm.sqls.doc/ids_sqs_0162.htm

The condition in the HAVING clause cannot include a DISTINCT or UNIQUE aggregate expression.

一种变通方法是让 select

中的计数不同

SELECT 
person,
count(distinct friend) as f_count
FROM people 
GROUP BY person 
HAVING f_count > 1;

更新：

查了资料，发现了事实

The HAVING clause is evaluated before the SELECT - so the server doesn't yet know about that alias.

所以要实现目标，可以这样做

select
person,
f_count
from(
 SELECT 
 person,
 count(distinct friend) as f_count
 FROM people
 GROUP BY person 
)x
where f_count > 1

Answer 4

只是通过使用更多分组依据的替代方法 -

select cust_xref_id
from(
select cust_xref_id,cm11
from temp_nippon_cust
group by cust_xref_id,cm11
) temp
group by cust_xref_id
having count(cm11) > 1

having子句中如何有'distinct'

How to have 'distinct' in having clause

sql

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