How to build a query involving several different tables with different relationships - mysql

Question

I'm currently trying to write a query which involves 5 main tables, 2 of which are referring to a 3rd with foreign keys, but not relating to each-other... and one of the first 2 tables is the main subject of the query. Here's a basic synopsis.
instance user
-------- ----
id id
name name
user_id
def def_map
--- ------
id id
name instance_id
user_id def_id
def_data
--------
id
name
def_id
user_id
What I want to do is get a list of all of the 'def_map's for a single user. In each row I'd like the associated def_data to be displayed as well. So the rows would be like:
instance.id, def.id, def.name, def_data.name, user.id
I can figure out how to get all info except def_data.name in the result, or all info except for instance.id ... but can't figure out how to get then all together using one query. Is it possible? I think part of the problem is I don't know if there is a special word that describes this type of query so I would know what to read up on.
I'm using DQL, but examples in SQL would be just as useful. Thanks in advance for any help.

Answer 1

If you can pull the data individually using 2 queries you simply need to UNION them together
SELECT user.id, i.id, d.id, dd.name
FROM user u
INNER JOIN instance i ON u.id=i.user_id
INNER JOIN def d ON dm.user_id = u.id
INNER JOIN def_data dd ON dd.def_id = d.id
UNION ALL
SELECT u.id, i.id AS instance_id, d.id, dd.name
FROM instance i
INNER JOIN user u ON u.id=i.user_id
INNER JOIN defmap dm ON dm.instance_id=i.id
INNER JOIN def_data dd ON dd.def_id=dm.def_id

Answer 2

select I.id, D.id, D.name, DD.name, U.id
from user U inner join instance I on I.user_id = U.id
Inner join def D on D.user_id = U.id
inner join def_map DM on DM.def_id = D.id AND I.id = DM.instance_id
inner join def_data DD on DD.def_id = D.id AND U.id = DD.user_id
Test data:
USER
+----+-------------------------+
| id | name |
+----+-------------------------+
| 1 | Name1 |
+----+-------------------------+
Instance
+----+------+---------+
| id | name | user_id |
+----+------+---------+
| 1 | I1 | 1 |
+----+------+---------+
def_map
+--------+-------------+--------+
| id | instance_id | def_id |
+--------+-------------+--------+
| 1 | 1 | 1 |
+--------+-------------+--------+
def
+--------------+------+
| id | name | user_id |
+--------------+------+
| 1 | df1 | 1 |
+--------------+------+
def_data
+--------+------+--------+---------+
| id | name | def_id | user_id |
+--------+------+--------+---------+
| 1 | dd1 | 1 | 1 |
+--------+------+--------+---------+
Result
+-------------+--------+----------+---------------+---------+
| instance.id | def.id | def.name | def_data.name | user.id |
+-------------+--------+----------+---------------+---------+
| 1 | 1 | df1 | dd1 | 1 |
+-------------+--------+----------+---------------+---------+