Question

I am trying to do something like

SELECT * from accounttable, peopletable, companytable 
WHERE if accounttable.account_type = company 
JOIN companytable 
WHERE companytable.id = accounttable.company_id 
ELSE IF accounttable.account_type = = person 
JOIN peopletable 
WHERE peopletable.id = accounttable.person_id

I’m sorry its a bit sqlenglish, but I really don’t know how to write it out.

Answer 1

What about something like:

SELECT * 
from accounttable
left join peopletable ON (accounttype = 'person' AND peopletable.id = accounttable.person_id)
left join companytable ON (accounttype = 'company' AND companytable.id = accounttable.company_id)

I’ll join against both tables, so you’ll have fields of all three tables in the output. The fields from peopletable will be NULL if accounttype != 'person', and those of companytable will be NULL where accounttype != 'company'.

You can find more on the LEFT JOIN syntax in places like here…