Question

I’m building this bartering-type function in this site using PHP/MySQL and I’m trying to create a query that responds with the following fields:
owner’s username, title, offerer’s username, offerer’s item

Basically I have three tables here with the following fields:

users

user_id, username, email 

items_available

item_number, owner_id (foreign key that links to user_id), title

offers_open

trade_id, offerers_id (fk of user_id), offerers_item(fk with item_number), receivers_id (fk from user_id)

How do I do this? I’ve seen some references to many-to-many SQL queries but they don’t seem to particularly fit what I’m looking for (for example, the offerers_id and the owner_ids refer to different users_id in the Users table, but how do I make them distinguishable in the sql query?)

Answer 1

If I understand correctly, this is what you are looking for:

SELECT owner.username, oferrers.username, ia.title
FROM offers_open o
  INNER JOIN users AS offerers
    ON o.offerers_id = offerers.user_id
  INNER JOIN items_available AS ia
    ON o.offerers_item= ia.item_number
  INNER JOIN users AS owner
    ON ia.owner_id = owner.user_id

I don’t see a title on the users table, so didn’t include one.