Question

我一直在努力寻找能够更好地满足我特定需求的例子，但我似乎找不到任何例子。

我有以下SQL语句，它就像一个魅力：

SELECT
 customers.id,
 customers.customer_name,
 SUM(shipments.balance) AS shipmentBalance

 FROM customers

 LEFT JOIN shipments ON customers.id = shipments.bill_to
 GROUP BY customers.id, customers.customer_name
 ORDER BY shipmentBalance DESC;

但是，我希望能够在JOIN中添加where条件，因为我不希望所有的货运余额都被提升，而只是那些余额大于相关支付分配金额的货币。

此时，在单独的查询中，我可以使用以下查询提取余额大于其付款分配金额的货件：

SELECT
  shipments.id,
  shipments.pro_number,
  shipments.balance,
  SUM(payments_distributions.amount) AS Sum
FROM
  shipments

LEFT JOIN payments_distributions ON shipments.pro_number = payments_distributions.shipment_id
WHERE balance > (SELECT IFNULL(SUM(payments_distributions.amount),0) FROM payments_distributions WHERE payments_distributions.shipment_id = pro_number)
GROUP BY shipments.id,shipments.pro_number;

但我不确定如何将它们结合起来。

Answer 1

将Shipment表的过滤器放在ON子句中：

SELECT
customers.id,
customers.customer_name,
SUM(shipments.balance) AS shipmentBalance
FROM customers
LEFT JOIN shipments ON customers.id = shipments.bill_to
   AND balance > (SELECT IFNULL(SUM(payments_distributions.amount),0) 
                  FROM payments_distributions 
                  WHERE payments_distributions.shipment_id = pro_number)
GROUP BY customers.id, customers.customer_name
ORDER BY shipmentBalance DESC;

加入Where子句 - 嵌套加入/在哪里？

1 个答案: