Question

I’ve got 3 tables that are something like this (simplified here ofc):

• users
  • user_id
  • user_name
• info
  • info_id
  • user_id
  • rate
• contacts
  • contact_id
  • user_id
  • contact_data

users has a one-to-one relationship with info, although info doesn’t always have a related entry.

users has a one-to-many relationship with contacts, although contacts doesn’t always have related entries.

I know I can grab the proper ‘users’ + ‘info’ with a left join, is there a way to get all the data I want at once?

For example, one returned record might be:

user_id: 5
user_name: tom
info_id: 1
rate: 25.00
contact_id: 7
contact_data: 555-1212
contact_id: 8
contact_data: 555-1315
contact_id: 9
contact_data: 555-5511

Is this possible with a single query? Or must I use multiple?

Answer 1

Each row of result must have the same columns, so you can’t aggregate multiple rows of contact not having the other columns as well.

Hopefully, this query would achieve what you need:

SELECT
    u.user_id as user_id,
    u.user_name as user_name,
    i.info_id as info_id,
    i.rate as rate,
    c.contact_id as contact_id,
    c.contact_data as contact_data
FROM users as u
LEFT JOIN info as i ON i.user_id = u.user_id
LEFT JOIN contacts as c ON c.user_id = u.user_id