Question

我有一张数据如下的表

ID Classroom Person
1   1         Alfred
2   1         Maria
3   2         Maria
4   2         Zoe
5   2         Alfred
6   3         Nick
7   3         Paul
8   3         Mike
9   3         Alfred
10  4         Zoe
11  4         Maria

我想选择并仅返回仅以人为主的课堂＆＃39; Alfred＆＃39;和玛丽亚＆＃39; 以下声明：

Select * from table_name where (Person='maria') and (Person=Alfred')

似乎不起作用。

你c an see a SQL Fiddle here，

Answer 1

您可以使用group by和having：

select classroom
from table t
group by classroom
having count(*) = 2 and
       sum(person in ('maria', 'Alfred')) = 2;

这假设一个人不能多次在教室里。

这会检查课堂上有两个名字，它们是两个感兴趣的名字。如果你有重复项，你可能需要：

having count(distinct name) = 2 and
       count(distinct case when person in ('maria', 'Alfred') then person end) = 2;

Answer 2

试试这个。 Group by and having Count应该有效。

SELECT Classroom
FROM   tablename
WHERE  Person IN( 'maria', 'Alfred' )
GROUP  BY classroom
HAVING Count(Person) = 2

选择多个值SQL

2 个答案: