Question

Say that you have a table with two (or more) columns which link to another table:

 house_history         houses
---------------       --------
OwnerID               HouseID
PreviousHouseID       Address
CurrentHouseID

and you wanted to return data from each of those IDs:

---------------------------------------------------------------
|OwnerID|        PreviousAddress    |      CurrentAddress     |
---------------------------------------------------------------
         (linked to PreviousHouseID) (linked to CurrentHouseID)

How would you go about doing that? (specifically I’m interested in using MySQL)

Answer 1

SELECT OwnerId, p.Address as PreviousAddress, c.Address as CurrentAddress
FROM house_history h
LEFT JOIN houses p ON h.PreviousHouseID = p.HouseID
LEFT JOIN houses c ON h.CurrentHouseID = c.HouseID