Question

I have 3 tables:

addresses

id, address, city, zipcode

persons (1500 records)

id, address_id, firtname, lastname, sex, title

buildings (100 records)

id, address_id, name, type_of_building

Multiple persons/buildings share the same address. I need to list all addresses with its person or building info. So, my query should return a total of 1600 records.

What kind of query do I need to write to retrieve this information?

Answer 1

Because you need all of the records from two different datasets, you need to use an INNER JOIN with a UNION. Something like this might work:

SELECT p.id, p.firstname, p.lastname, p.sex, p.title, a.address, a.city, a.zipcode
FROM persons p
  INNER JOIN addresses a on a.id = p.address_id

UNION ALL

SELECT b.id, b.name, '', '', b.type_of_building, a.address, a.city, a.zipcode
FROM buildings b
  INNER JOIN addresses a on a.id = b.address_id