如何从此多对多表中选择

Question

Database: mySQL

What I am looking for is: A way to select a list of users that has status X with User X. Let's say my name is James and I want to get my friends list. Is this possible?

Tabel User:
-- ID
-- first_name
-- last_name
...

Tabel User_Status:
-- User_ID1
-- User_ID2
-- Status

The result I want should look something like this: Let's say my user ID = 0.

User_ID1-----User_ID2-----Status
------0---------------1-----------friends
------0---------------2-----------friends
------0---------------3-----------friends
------0---------------4-----------friends
------0---------------5-----------friends

Answer 1

mysql> select * from User;
+----+------------+-----------+
| ID | first_name | last_name |
+----+------------+-----------+
|  1 | Nikolai    | Tesla     |
|  2 | Albert     | Einstein  |
|  3 | Bertrand   | Russell   |
|  4 | Carl       | Sagan     |
+----+------------+-----------+
4 rows in set (0.00 sec)

mysql> select * from User_Status;                                                                    +----------+----------+---------------+
| User_ID1 | User_ID2 | Status        |
+----------+----------+---------------+
|        1 |        2 | FRIENDS       |
|        1 |        3 | FRIENDS       |
|        2 |        1 | FRIENDS       |
|        3 |        4 | ACQUAINTANCES |
|        3 |        1 | FRIENDS       |
+----------+----------+---------------+

mysql> SELECT u.* 
       FROM User u   
       JOIN User_Status us ON u.ID = us.User_ID1 
       WHERE us.Status = "FRIENDS" AND us.User_ID2 = 1;
+----+------------+-----------+
| ID | first_name | last_name |
+----+------------+-----------+
|  2 | Albert     | Einstein  |
|  3 | Bertrand   | Russell   |
+----+------------+-----------+
2 rows in set (0.00 sec)