错误1054。MySQL中“ on子句”中的未知列

Question

I have 2 tables in dataset: price change and built_used_area.

I need to calculate average price change (from 1st table) over built_area (from second) for specific observations.

I tried this query, but it didnt work.

select (avg((new_price-old_price)/old_price))/built_area from 
    (select * from price_change where year(change_date)=2016 and new_price > old_price) as T
    join built_used_area on (price_change.listing_id = built_used_area.listing_id);

Any ideas how to fix this?

Thanx for you help in advance.

Answer 1

solved with:

SELECT 
    AVG(new_price / built_area)
FROM
    (SELECT 
        new_price, built_area, change_date
    FROM
        price_change, built_used_area
    WHERE
        YEAR(change_date) = 2016
            AND new_price > old_price
            AND new_price > 0
            AND old_price > 0
            AND (built_area > 200 OR used_area > 200)) AS T;