Question

在查询中Sum函数之前是否有可能进行某种连接？我有以下问题：

SELECT 
  orders.id AS orderId,
  orders.delivery_from,
  orders.delivery_to,
  orders_products.product_id,
  orders_products.color_id,
  orders_products.size_id,
  SUM(orders_products.quantity) AS quantity,
  customers.id AS customerId,
  customers.name AS customerName,
  products.name 
FROM
  orders 
  INNER JOIN orders_products 
    ON orders_products.order_id = orders.id 
  INNER JOIN customers 
    ON customers.id = orders.customer_id 
  INNER JOIN products 
    ON orders_products.product_id = products.id 
  LEFT JOIN orders_product_data 
    ON orders_product_data.order_id = orders.id 
    AND orders_product_data.product_id = orders_product.product_id 
    AND orders_product_data.color_id = orders_product.color_id 
WHERE orders.status = '0' 
  AND (
    orders.delivery_from <= '2014-05-05' 
    AND orders.delivery_to >= '2014-05-05'
  ) 
  AND (
    (orders_products_data.delivery_from <= '2014-05-05' || orders_products_data.delivery_to = 0) 
    AND (orders_products_data.delivery_from >= '2014-05-05' || orders_products_data.delivery_to = 0)
  ) 
GROUP BY customer_id,
  product_id,
  color_id,
  size_id

我想为每位客户订购的产品数量。当然，我可以通过内部联接来计算这个，但是有一种更好的方法吗？

Answer 1

从评论开始，您可以使用subselect进行额外的加入，这将是内部联接，并且只会获得产品超过400的客户

SELECT
  GROUP_CONCAT(DISTINCT CONVERT(o.id, CHAR(11))) orders, 
  o.delivery_from,
  o.delivery_to,
  o.customer_id,
  op.product_id, 
  op.color_id,
  op.size_id,
  sum(op.quantity) as quantity
FROM orders o
  INNER JOIN orders_products op  ON op.order_id=o.id
  LEFT JOIN orders_products_data opd ON opd.order_id=o.id 
AND opd.product_id=op.product_id
AND opd.color_id=op.color_id
JOIN (SELECT customer_id FROM orders o
      JOIN orders_products op ON(op.order_id=o.id)
     GROUP BY customer_id
      HAVING SUM(op.quantity) >400
     ) t
ON(o.customer_id = t.customer_id)
WHERE
  o.status='0' AND
  (o.delivery_from <= '2014-05-05' 
   AND o.delivery_to >='2014-05-05') 
   AND
  ((opd.delivery_from<='2014-05-05' 
    || opd.delivery_to=0) 
     AND (opd.delivery_from>='2014-05-05' ||
          opd.delivery_to=0))
GROUP BY o.customer_id ,
op.product_id, 
op.color_id, 
op.size_id

对于上述查询，您应该为ON()子句中使用的列编制索引，并索引where过滤器中涉及的日期列

Mysql总和有点concat

1 个答案:

Demo