如何在mysql查询中获取最新的商品价格？

Question

I manage to get the lowest, highest and average price of the item but couldn't get the latest price. Below is the select query i am using by joining the item and item_price tables. How can I fix the problem?

$sql = 'SELECT *, MIN(ip_price) AS lowest_price, MAX(ip_price) AS highest_price, 
        AVG(ip_price) AS average_price, MAX(ip_price_date) AS latest_date,
        (SELECT ip_price FROM cnf_item_price WHERE ip_price_date = "latest_date") AS latest_price
        FROM cnf_item
        INNER JOIN cnf_item_price ON cnf_item_price.ip_item_id = cnf_item.it_id
        WHERE 1 AND cnf_item_price.ip_supp_id=?
        GROUP BY cnf_item.it_id
        ORDER BY cnf_item.it_name ASC';
$stmt = $DB->prepare($sql);
$stmt->bindValue(1,$supplier_id);
$stmt->execute();

Answer 1

can you try following query:

$sql = 'SELECT *, MIN(ip_price) AS lowest_price, MAX(ip_price) AS highest_price, 
        AVG(ip_price) AS average_price, MAX(ip_price_date) AS latest_date,
        (SELECT ip_price FROM cnf_item_price order by ip_price_date desc limit 1) AS latest_price
        FROM cnf_item
        INNER JOIN cnf_item_price ON cnf_item_price.ip_item_id = cnf_item.it_id
        WHERE 1 AND cnf_item_price.ip_supp_id=?
        GROUP BY cnf_item.it_id
        ORDER BY cnf_item.it_name ASC';
$stmt = $DB->prepare($sql);
$stmt->bindValue(1,$supplier_id);
$stmt->execute();

Answer 2

Thanks #ahmet kamaran. It's working for my case here. I also replace * with those columns needed as suggested by others. So, after some testing from the above suggestions, here is my codes which retrieve those data i needed.

$sql = 'SELECT it_id, it_code, it_name, it_desc, 
        ip_id, ip_item_id, ip_supp_id, ip_price, ip_price_date, ip_ref_no, ip_remarks, 
        MIN(ip_price) AS lowest_price, MAX(ip_price) AS highest_price,
        AVG(ip_price) AS average_price, MAX(ip_price_date) AS latest_date,
        (SELECT ip_price FROM cnf_item_price ORDER BY ip_price_date DESC LIMIT 1) AS latest_price
        FROM cnf_item
        INNER JOIN cnf_item_price ON cnf_item_price.ip_item_id = cnf_item.it_id
        WHERE 1 AND cnf_item_price.ip_supp_id=?
        GROUP BY cnf_item.it_id
        ORDER BY cnf_item.it_name ASC';

$stmt = $DB->prepare($sql);
$stmt->bindValue(1,$supplier_id);
$stmt->execute();

http://sqlfiddle.com/#!9/ca6234/2

Thanks.

Answer 3

SELECT it_id, it_code, it_name, it_desc, ip_id, ip_item_id, ip_supp_id, ip_price, ip_price_date, ip_ref_no, ip_remarks, MIN(ip_price) AS lowest_price, MAX(ip_price) AS highest_price, AVG(ip_price) AS average_price, MAX(ip_price_date) AS latest_date, (SELECT ip_price FROM cnf_item_price WHERE cnf_item_price.ip_item_id = cnf_item.it_id ORDER BY ip_price_date DESC LIMIT 1) AS latest_price FROM cnf_item INNER JOIN cnf_item_price ON cnf_item_price.ip_item_id = cnf_item.it_id WHERE 1 GROUP BY cnf_item.it_id ORDER BY cnf_item.it_name ASC;