Select all values from table B where matches table A - mysql

Question

I have this schema:
items | taxonomy | subjects
| |
ID headline | item_id subject_id | subject_id subject
-------------------------------------------------------------------------
1 information | 1 1 | 1 cities
2 here we are | 2 1 | 2 towns
3 more things | 3 2 | 3 water
4 doo dah | 3 4 | 4 telephones
| 4 1 |
| 4 3 |
I would like to select a single row from "items" and with it, include all the rows from "subjects" which are joined by the "taxonomy" table. So for example, getting item.ID=3 would result in something like:
items.ID = 3
items.headline = "more things"
subjects.subject = "towns"
subjects.subject = "telephones"
I've started with this query
SELECT
i.ID,
i.headline,
s.subject_name
FROM items i
JOIN taxonomy t
on i.ID=t.item_id
JOIN subjects s
on t.subject_id=s.subject_id
WHERE i.ID = 3
But this only returns a single value from subject_name even if there are multiple values associated with that item_id.
EDIT
I actually had a LIMIT 1 on the query which was causing (as #Gordon Linoff said) only one row to be returned, even though there were multiple rows in the result set corresponding to the multiple subjects. His solution still does nicely, because I only want to return a single row.

Answer 1

Your query returns the subjects on multiple rows. If you want the subjects on a single row, then you need some form of concatenation:
SELECT i.ID, i.headline, GROUP_CONCAT(s.subject_name) as subjects
FROM items i JOIN
taxonomy t
ON i.ID = t.item_id JOIN
subjects s
ON t.subject_id = s.subject_id
WHERE i.ID = 3
GROUP BY i.ID, i.headline;
For one item, the GROUP BY is optional, but it is good form in case you modify the query to handle multiple items.

Answer 2

I would suggest you the "union all" clause (or "union", if you are not needing the duplicates).
(SELECT
"taxonomy" As Name,
i.headline As Value
FROM items i
JOIN taxonomy t
on i.ID=t.item_id
WHERE i.ID = 3)
Union All
(SELECT
"subject" As Name,
s.subject_name As Value
FROM items i
JOIN subjects s
on t.subject_id=s.subject_id
WHERE i.ID = 3)
You can add a 2nd field in each select to indicate type of item selected ("headline", "subjects", etc).