如何在查询中总计结果

Question

我有以下查询：

SELECT cb.customers_id, cb.products_id, p.products_model, pd.products_name, cb.customers_basket_quantity, p.products_price, (p.products_price * cb.customers_basket_quantity) AS product_total
    FROM customers_basket cb, products p, products_description pd
    WHERE cb.customers_id =194075
        AND cb.products_id = pd.products_id
        AND p.products_id = pd.products_id

我试图找出是否可以获得“cart_total”而无需进行其他查询，或者使用PHP来保持运行总计。

我不确定我是否可以使用CASE语句来做某事。

建议？

Answer 1

SELECT cb.customers_id, cb.products_id, p.products_model, pd.products_name, cb.customers_basket_quantity, p.products_price, (p.products_price * cb.customers_basket_quantity) AS product_total,

(SELECT sum(p.products_price * cb.customers_basket_quantity) 
FROM customers_basket cb, products p
WHERE cb.customers_id =194075
AND cb.products_id = p.products_id
group by cb.customers_id) AS cart_total

FROM customers_basket cb, products p, products_description pd
WHERE cb.customers_id =194075
AND cb.products_id = pd.products_id
AND p.products_id = pd.products_id

指向 Fiddle

的链接

Answer 2

您可以执行购物车总数，但是您想要删除group by和select中的某些列（它们不适合购物车级别）。您还应该使用标准的ANSI连接语法：

SELECT cb.customers_id, cb.customers_basket_quantity,
       sum(p.products_price * cb.customers_basket_quantity) AS product_total
FROM customers_basket cb join
     products p
     on cb.products_id = p.products_id join
     products_description pd
     on p.products_id = pd.products_id
WHERE cb.customers_id = 194075
GROUP BY cb.customer_basket_id;

产品级别的信息在篮子级别没有意义。您可以创建产品名称列表，例如：

group_concat(p.products_name) as Products_Name

但是个人价值观没有意义。

Answer 3

试试这个，你将得到查询最后一行的结果总和。

所有其他列都将为空。

SELECT  cb.customers_id, 
        cb.products_id, 
        cb.customers_basket_quantity, 
        p.products_model, 
        p.products_price, 
        pd.products_name,
        (p.products_price * cb.customers_basket_quantity) AS product_total,
        null as cart_total
    FROM products p 
        INNER JOIN customers_basket cb ON p.products_id = cb.products_id
        INNER JOIN products_description pd ON pd.products_id = p.products_id
    WHERE cb.customers_id = 194075

union all

SELECT null, null, null, null, null, null, null,
        SUM(p.products_price * cb.customers_basket_quantity) AS cart_total
    FROM products p 
        INNER JOIN customers_basket cb ON p.products_id = cb.products_id
    WHERE cb.customers_id = 194075