How to convert this subquery in a join?

Question

Using this SO answer I've created the following query:

select 
    created, property_id, requesting_user_id, type, response 
from 
    pdr t1 
where 
    t1.created = (
        select max(created) 
        from pdr t2 
        where t2.property_id = t1.property_id and t2.requesting_user_id = t1.requesting_user_id
    )

This works like a charm, but now I want to transform this (also as suggested in the SO answer I linked above) to a query using a join. So I came up with this:

select 
    created, property_id, requesting_user_id, type, response 
from 
    pdr t1 
inner join (
    select max(created) as created, property_id, requesting_user_id
    from pdr
    group by property_id, requesting_user_id
) as t2 on t2.property_id = t1.property_id and t2.requesting_user_id = t1.requesting_user_id and t2.created = t1.created

Unfortunately this returns an error saying ambiguous column name: created . So I messed around with putting t1. or t2. before some of the created things, but then I get all sorts of syntax errors, so I'm kinda lost here.

Could anybody help me out in what I'm doing wrong here? All tips are welcome!

ps: I'm currently testing this on SQLite, but in the end it should work on MySQL as well. If there is a difference that would of course be very interesting to know also.

Answer 1

First select should be like:

SELECT t1.created, t1.property_id, t1.requesting_user_id, type, response...

Everything else you done correctly...

based on https://dev.mysql.com/doc/refman/5.1/en/example-maximum-column-group-row.html ...

GL