Question

编写查询以显示已取消票证的用户名和用户名，并按user_id按升序显示记录。我的代码：

SELECT u.user_id, name
FROM users u JOIN tickets t
ON u.user_id= t.user_id JOIN
cancellation c
ON t.ticket_id = c.ticket_id
WHERE cancellation_id IN 'cancel'
ORDER BY user_id;

这不会显示任何输出

Answer 1

联接类型和联接顺序很重要。有关明确说明，请参阅MySQL Join Made Easy。试试这个：

SELECT u.user_id, u.name
FROM cancellation c JOIN tickets t
ON t.ticket_id = c.ticket_id
JOIN users u ON u.user_id= t.user_id JOIN
WHERE cancellation_id='cancel'
ORDER BY u.user_id;

Answer 2

select u.user_id, u.name 
from users u join tickets t 
on u.user_id=t.user_id
join cancellation c on t.ticket_id=c.ticket_id 
order by u.user_id;

Answer 3

这肯定会起作用

select u.user_id,u.name
    from((users u inner join tickets t
    on u.user_id=t.user_id)
    inner join cancellation c
    on t.ticket_id=c.ticket_id)
    where cancellation_id is not null
    group by u.user_id,u.name
    order by u.user_id;

Answer 4

select users.user_id,users.name
    from users join tickets 
    ON users.user_id = tickets.user_id
    join cancellation on
    tickets.ticket_id = cancellation.ticket_id
    where cancellation_id is not null
    order by user_id

Answer 5

使用子查询

select 
    u.user_id,
    u.name
    from users u
    where user_id in 
    (select 
    user_id from tickets
    inner join cancellation on tickets.ticket_id
     = cancellation.ticket_id)
    order by user_id asc;

加入sql。用户详细信息基于取消

5 个答案: