Question

我有以下查询：

SELECT od.product_id, od.product_name, od.product_quantity, od.product_price,
        o.id_address_delivery, a.id_country, a.id_state, s.name
FROM `ps_order_detail` od
LEFT JOIN ps_orders AS o ON od.`id_order` = o.`id_order`
LEFT JOIN `ps_address` AS a ON o.`id_address_delivery` = a.`id_address`
LEFT JOIN `ps_state` AS s ON a.id_state = s.id_state
ORDER BY o.`date_add` DESC
LIMIT 100;

返回如下数据：

product_id | product_name | product_qty | product_price | id_state

我想知道每个州的畅销书（就数量而言）。例如：

A国：畅销商品为A（500件已售出数量） B国：畅销商品C商品（已售出150件）状态C：畅销产品是产品A（100个销售数量）

目前我正在考虑在两列之间进行联接，但第二次认为这需要一个类似“枢轴”的功能。

我知道如何获得每种产品的总销售数量

SELECT od.product_id, od.product_name, COUNT(od.product_id) AS 'total'
FROM `ps_order_detail` od
GROUP BY od.product_id
ORDER BY od.product_id DESC
LIMIT 100;

我也知道每个州的总销售数量，但我不知道如何将两者结合起来以实现我所需要的。我很感激任何帮助。感谢

Answer 1

您需要聚合查询的groupwise最大值。你可以这样做，例如像这样：

select state, product_name, quantity
from (
  select id_state, state, product_id, product_name, quantity,
    @grprow := (case when @grp = id_state then @grprow + 1 else 1 end) as grprow,
    @grp := id_state
  from  ( 
    SELECT a.id_state, max(s.name) as state, od.product_id, 
         max(od.product_name) as product_name,
         sum(od.product_quantity) as quantity
    FROM `ps_order_detail` od
    LEFT JOIN ps_orders AS o ON od.`id_order` = o.`id_order`
    LEFT JOIN `ps_address` AS a ON o.`id_address_delivery` = a.`id_address`
    LEFT JOIN `ps_state` AS s ON a.id_state = s.id_state
    group by a.id_state, od.product_id
  ) grped,
  (select @grprow := 0, @grp := null) init
  order by id_state, quantity desc, product_id
) grpmax
where grprow = 1
order by id_state;

它将每个州和产品的数量相加，然后对每个州的结果进行编号，然后取第一个。如果两个产品在一个状态中具有相同的数量，则仅采用其中一个（具有较低的product_id）。如果您想同时使用两者，则可以调整@grprow的编号条件。

对多列进行分组

1 个答案: