MySQL get value using data from three tables - mysql

Question

I need to get one value from one table using information from other two.
Here is the structure:
USERS TABLE
+-----------+---------+------------+
| ID | NAME | ZIP |
+-----------+---------+------------+
| 1 | John | 1111-222 |
| 2 | Maria | 2222-555 |
| 3 | José | 3333-505 |
+-----------+---------+------------+
ZIP-MATCH TABLE
+-----------+---------+------------+------------+
| DD | CC | PART1 | PART2 |
+-----------+---------+------------+------------+
| 1 | 1 | 1111 | 101 |
| 1 | 1 | 1111 | 111 |
| 1 | 2 | 1111 | 222 |
| 1 | 3 | 2222 | 333 |
| 2 | 1 | 2222 | 100 |
| 2 | 1 | 2222 | 555 |
| 2 | 2 | 2244 | 222 |
| 2 | 2 | 2244 | 333 |
| 2 | 3 | 2245 | 311 |
| 3 | 1 | 3333 | 111 |
| 3 | 2 | 3333 | 222 |
| 3 | 3 | 3333 | 505 |
+-----------+---------+------------+------------+
AREAS NAME TABLE
+-----------+---------+------------+
| DD | CC | AREA |
+-----------+---------+------------+
| 1 | 1 | Lisboa |
| 1 | 2 | Porto |
| 1 | 3 | Aveiro |
| 2 | 1 | Braga |
| 2 | 2 | Fundão |
| 2 | 3 | Bogas |
| 3 | 1 | Faro |
| 3 | 2 | Leiria |
| 3 | 3 | Covilhã |
+-----------+---------+------------+
What I need to do is a query to get all users from the first table, with all the users data (ID, NAME, ZIP) plus the AREA name.
For this example it would be:
1, John, 1111-222, Porto
2, Maria, 2222-555, Braga
3, José, 3333-505, Covilhã
Thanks in advance,
Miguel.

Answer 1

This is the answer:
SELECT
a.id,
a.name,
a.zip,
c.area
FROM
users a
LEFT JOIN
zip_match b
ON a.zip = concat(b.part1,'-',b.part2)
LEFT JOIN
areas_name c
ON b.dd = c.dd
and b.cc = c.cc;
Assuming your tables were called users, zip_match and areas_name respectively. Not sure of the data types of part1 and part2, they might need to be converted into strings to work in the concat function.

Answer 2

select users.id, users.name, users.zip, areas.area from users u, zipmatch z, areas a
where u.zip = z.part1 + '-' + z.part2
and a.dd = z.dd and a.cc = z.cc
perhaps?