mysql - MYSQL IF ELSE? What is the correct statement to use (stock from multiple suppliers)

Question

I have a database in phpmyadmin for all my suppliers. I have created a php file that exports to csv on a daily basis the cheapest stock and quantity of each unique sku in the database. At the moment however, it is excluding any item that has no stock anywhere, however, i would like that... if there is no stock anywhere to print 0 for those items.

The original sql statement is (where name=SKU):

SELECT name,MIN(price) AS minPrice,quantity FROM products WHERE quantity > 0 GROUP BY name

I tried already the following, but this does not work as intended:

SELECT name,MIN(price) AS minPrice,IF(quantity > 0,quantity,'0') AS quantity FROM products GROUP BY name

Answer 1

你想要条件聚合：

SELECT name, MIN(price) AS minPrice, coalesce(sum(quantity), 0) AS quantity 
FROM products
GROUP BY name;

您的查询的问题是where过滤掉所有产品 where quantityis的子句0。你似乎真的想要这些。

我已经包括了以防coalesce()万一。您的实际数据可能不需要它。quantityNULL

Answer 2

如果您正在寻找价格最低的产品数量，请尝试：

SELECT  name
,       price
,       coalesce(quantity,0) as quantity
FROM    products p1
WHERE   price = 
        (
        SELECT  min(price)
        FROM    products p2
        WHERE   p1.name = p2.name
        )