Question

I have the following tables:

Teams

+------+--------------+--------------+
| id   |  team_name   |  team_code   |
+------+--------------+--------------+
|  1   |  Wales       | WAL          |
|  2   |  England     | ENG          |
|  3   |  New Zealand | NZL          |
+------+--------------+--------------+

Matches

+------+-----------+-----------+
| id   |  team_a   |  team_b   |
+------+-----------+-----------+
|  1   |  WAL      | ENG       |
|  2   |  ENG      | NZL       |
|  3   |  WAL      | NZL       |
+------+-----------+-----------+

I know how a join works, but I can’t get my head around how I can query to the database by Matched.id to get the team name for BOTH teams from the Teams database. Let me explain better

• For each match I need to determine the team names
• I will query by Matches.id
• So for Match: 1 I’ll need to select ‘Wales’ and ‘England’

Hope I’ve explained my problem clearly enough, but If I haven’t please feel free to ask more questions

Answer 1

The database structure seems to be “off” to me.

You should have both team_a and team_b as foreign keys to the Teams table primary key.

You can then join on the IDs (twice) to get the full names.

Matches:

+------+-----------+-----------+
| id   |  team_a   |  team_b   |
+------+-----------+-----------+
|  1   |  1        | 2         |
|  2   |  2        | 3         |
|  3   |  1        | 3         |
+------+-----------+-----------+

SELECT T1.team_name, T2.team_name
FROM Matches M
  INNER JOIN Teams T1
    ON M.team_a = T1.id
  INNER JOIN Teams T2
    ON M.team_b = T2.id
WHERE M.id = 1