想知道用户上传了多少张照片。统计表。 SQL

Question

我的数据库中有两个表

members (member_id, firstname, lastname)
members_photos (member_id, photo_id) 

基本上我希望能够以这种方式查询数据以显示以下内容

User     Number of photos uploaded
George   15
Steven   3
Mark     0

任何帮助？

Answer 1

select firstname, count(*) 
from members 
join member_photos using(member_id) 
group by firstname

Answer 2

您需要连接两个表，然后计算行数。

SELECT 
    [firstname] as [User], 
    count(*) as [Number of photos uploaded]
FROM
    [members] m
    INNER JOIN [members_photos] mp
    ON m.[member_id] = mp.[member_id]