Question

SELECT
    Tickets.id,
    (SELECT Users.Name FROM Users INNER JOIN Tickets ON Tickets.Creator = Users.id) AS naam,
    (SELECT Users.Name FROM Users INNER JOIN Tickets ON Tickets.Owner = Users.id) AS name
FROM Tickets
WHERE Tickets.id = 64;

我想要一行

id, username(Tickets.creator= Users.id), username(where Tickets.Owner = Users.id)

Users

id | name
----------
1  | jan
2  | henk
3  | maria

tickets

ticketsid | owner     | creator
-------------------------------
1         | 3         | 2
2         | 1         | 3
3         | 2         | 3

Answer 1

您的查询希望与外部查询相关联。你错过了通过对tickets进行额外加入：

SELECT
    Tickets.id,
    (SELECT Users.Name FROM Users WHERE Tickets.Creator = Users.id) AS naam,
    (SELECT Users.Name FROM Users WHERE Tickets.Owner = Users.id) AS name
FROM Tickets
WHERE Tickets.id = 64;

您还可以使用join s表达此查询：

select t.id, uc.name as CreatorName, uo.name as OwnerName
from Tickets t left outer join
     Users uc 
     on t.Creator = uc.id left outer join
     Users uo
     on t.Owner = uo.id
where t.id = 64;

这是表达此查询的更典型方式。

Answer 2

怎么样

select t.id, o.name, c.name
  from tickets t
  join users o on o.id = t.owner
  join users c on c.id = t.creator
 where t.id = 64;

在一行上返回SQL查询的结果

2 个答案: