需要帮助MySQL查询。需要来自两个表的数据

Question

我是MySQL的初学者。

表1：用户

ID   NAME
----------
1    XYZ
2    ABC

表2：任务

ID   TASK_NAME   ASSIGNED_BY    ASSIGNED_TO
--------------------------------------------
1    task 1         1               2 
2    task 2         2               1 

我想要这个结果。

ID   TASK_NAME   ASSIGNED_BY    ASSIGNED_TO
--------------------------------------------
1    task 1         XYZ             ABC 
2    task 2         ABC             XYZ 

Answer 1

这是一个简单的JOIN任务：

SELECT t.ID, t.TASK_NAME, 
       u1.NAME AS ASSIGNED_BY,
       u2.NAME AS ASSIGNED_TO
FROM Task AS t
JOIN Users AS u1 ON t.ASSIGNED_BY = u1.ID
JOIN Users AS u2 ON t.ASSIGNED_TO = u2.ID

Answer 2

您需要使用INNER JOIN来执行此操作。我使用SELECT t.ID, t.TASK_NAME, u1.NAME AS ASSIGNED_BY, u2.NAME AS ASSIGNED_TO FROM Task AS t INNER JOIN Users AS u1 ON t.ASSIGNED_BY = u1.ID INNER JOIN Users AS u2 ON t.ASSIGNED_TO = u2.ID 请尝试以下查询。

parfor