mysql group_by只返回第一行

Question

I'm new here and and need some help with mysql query.

I have this query to retrieve several rows in a join query.

SELECT   category.category, category_color.color,
SUM(sales.quantity) AS quantity, SUM(sales.price) AS total, sales.id_payment_type,
                    sales.price
                FROM sales
            INNER JOIN 
                category        USING (id_category)
            INNER JOIN 
                shop_session    USING (id_shop_session)
            INNER JOIN 
                category_color  USING (id_category)
            WHERE shop_session.is_active = 1
            AND category.id_lang = "._ID_LANG_."
            AND shop_session.id_shop = ".$_SESSION['id_shop']."
            GROUP BY category.category
            ORDER BY category.category

I've achieved grouping by category is the first purpose , but when I need to retrive some data like "price" or "id_payment_type" mysql only returns the first row, and I need to get all rows from the query. I don't know how can I solve this query. Please help!

My sales db structure:

CREATE TABLE IF NOT EXISTS `sales` (

id_sale int(11) NOT NULL AUTO_INCREMENT, id_product int(11) unsigned NOT NULL, id_category int(11) unsigned NOT NULL, id_employee int(11) unsigned NOT NULL, id_payment_type int(11) unsigned NOT NULL, id_sale_type int(11) unsigned NOT NULL, id_shop_session int(11) unsigned NOT NULL, position int(11) NOT NULL, quantity int(11) NOT NULL, price decimal(17,2) NOT NULL, amount float NOT NULL, invoice int(1) NOT NULL, note varchar(150) COLLATE utf8_unicode_ci NOT NULL, date_sale int(11) DEFAULT NULL, PRIMARY KEY ( id_sale , id_product , id_category , id_employee , id_payment_type , id_sale_type , id_shop_session ), KEY id_sale ( id_sale ) )

And this is my db structure for category table:

CREATE TABLE IF NOT EXISTS `category` (

id_category int(10) unsigned NOT NULL, id_lang int(10) unsigned NOT NULL, category varchar(30) COLLATE utf8_unicode_ci NOT NULL, is_active int(1) NOT NULL )

Answer 1

SELECT   category.category, category_color.color,
SUM(sales.quantity) AS quantity, SUM(sales.price) AS total, sales.id_payment_type,
sales.price FROM sales
INNER JOIN  category        USING (id_category)
INNER JOIN  shop_session    USING (id_shop_session)
INNER JOIN  category_color  USING (id_category)
WHERE shop_session.is_active = 1
AND category.id_lang = "._ID_LANG_."
AND shop_session.id_shop = ".$_SESSION['id_shop']."
GROUP BY category.category
ORDER BY category.category

This query will give you the first row of every category you have because you are using a group by and i say the first because you are using an order by with an implicit ASC.

If you want all the id_payment_type or prices of every category you can't group by.