为什么添加计数（）到我的SQL查询停止它的工作？

Question

为什么这回23列（适量）：

select users.user_id, users.fname, users.lname, 
     stars.stars, comments.comment from users 
     LEFT JOIN stars on users.user_id = stars.userid 
     JOIN comments on users.user_id = comments.sender 
     where users.user_id = ? order by comments.time desc; 

，这回1行？：

select users.user_id, users.fname, users.lname, 
     stars.stars, count(distinct comments.id) as amount, 
     comments.comment from users 
     LEFT JOIN stars on users.user_id = stars.userid 
     JOIN comments on users.user_id = comments.sender 
     where users.user_id = ? order by comments.time desc; 

干杯。

Answer 1

您需要对主要数据进行分组或为该字段执行子查询。