mysql - 加入两个表而不返回不需要的行

Question

我的表结构是这样的:

      tbl.users                       tbl.issues
+--------+-----------+   +---------+------------+-----------+
| userid | real_name |   | issueid | assignedid | creatorid |
+--------+-----------+   +---------+------------+-----------+
|   1    |   test_1  |   |    1    |     1      |     1     |
|   2    |   test_2  |   |    2    |     1      |     2     |
+--------+-----------+   +---------+------------+-----------+

基本上我想编写一个查询，它将以如下所示的结果表结尾:

                           (results table)
+---------+------------+---------------+-----------+--------------+
| issueid | assignedid | assigned_name | creatorid | creator_name |
+---------+------------+---------------+-----------+--------------+
|    1    |     1      |    test_1     |    1      |    test_1    |
|    2    |     1      |    test_1     |    2      |    test_2    |
+---------+------------+---------------+-----------+--------------+

目前我的 SQL 看起来像这样:

SELECT 
  `issues`.`issueid`,
  `issues`.`creatorid`,
  `issues`.`assignedid`,
  `users`.`real_name`
FROM `issues`
JOIN `users` 
  ON ( `users`.`userid` = `issues`.`creatorid` )
  OR (`users`.`userid` = `issues`.`assignedid`)
ORDER BY `issueid` ASC
LIMIT 0 , 30 

这会返回如下内容:

                (results table)
+---------+------------+-----------+-----------+
| issueid | assignedid | creatorid | real_name |
+---------+------------+-----------+-----------+
|    1    |     1      |     1     |   test_1  |
|    2    |     1      |     2     |   test_1  |
|    2    |     1      |     2     |   test_2  |
+---------+------------+-----------+-----------+

谁能帮我得到想要的结果表？

Answer 1

SELECT 
  IssueID, 
  AssignedID, 
  CreatorID, 
  AssignedUser.real_name AS AssignedName, 
  CreatorUser.real_name AS CreatorName
FROM Issues
  LEFT JOIN Users AS AssignedUser
         ON Issues.AssignedID = AssignedUser.UserID
  LEFT JOIN Users AS CreatorUser
         ON Issues.CreatorID = CreatorUser.UserID
ORDER BY `issueid` ASC
LIMIT 0, 30