SQL查询跨越两个表

Question

我有两个SQL表匹配列：users & userGroup有类似的数据：

用户：

user  | age | gender 

    testUserA, 25, Male 
    testUserB, 30, Female 
    testUserC, 35, Male 

userGroup表示：

user  | group 

testUserA, groupA 
testUserB, groupA 
testUserC, groupB 

我会如何短语查询列出男性用户s在A组？

Answer 1

所有你需要的是一个join和where条款过滤gender和group：

select u.user 
from user u 
join userGroup ug on u.user = ug.user 
where u.gender = 'Male' 
    and ug.group = 'groupA' 

Answer 2

该查询会将两个表连接在一起，并按性别进行过滤。

SELECT u.User, u.Gender, ug.Group 
FROM user u 
INNER JOIN userGroup ug 
ON u.user = ug.user 
WHERE u.gender = 'Male' 
AND ug.Group = 'groupA'; 

Answer 3

下面是做这件事：

select a.user, a.age, a.gender, b.group from users as a 
inner join userGroup as b on a.user=b.user 
where a.gender='Male' and b.group='groupA'