Sql子查询比较两个计数

Question

我有以下查询返回具有类型“C”的寄存器的所有人以及具有类型“C”的每个人的行数。每个人都可以输入'C'或输入'V'

select count(type), number_document 
from register 
where type = 'C' 
group by number_document ;

我想只返回他所有行都有类型'C'的人，所以我需要做一个子查询，将总行数与count（类型）进行比较。

我不知道如何在这里引入子查询。

Answer 1

您可以使用NOT EXISTS来排除同样具有“V”类型的用户：

select count(type), number_document 
from register ro 
where type = 'C' 
    AND NOT EXISTS 
   (SELECT TOP 1 NULL 
    FROM register ri 
    WHERE ri.User = ro.User 
        AND ri.type='V')
group by number_document;

Answer 2

这对你有用吗？

select count(r.type), r.number_document 
from register r
where r.type = 'C' AND NOT EXISTS (
    SELECT *
    FROM register r2
    WHERE r.number_document = r2.number_document AND r2.type <> 'C'
)
group by r.number_document ;

Answer 3

下面的查询有两个条件

1. 过滤寄存器，所有'类型'值都相同
2. 然后筛选'C'类型的人

   select count(r.type), r.number_document 
   from register r
   where r.type = ALL (
       SELECT r2.type
       FROM register r2
       WHERE r.number_document = r2.number_document
   )
   AND r.type = 'C'
   group by r.number_document ;

Answer 4

这个怎么样？ HAVING子句检查唯一的TYPE列值是否为'C'（因为MIN = MAX = C）。

select number_document, count(*)
from register
group by number_document
having min(type) = max(type) and min(type) = 'C';