MySQL-每个项目的总销售额

下面的mysql查询用于获取用户id 31在2014年购买的每件商品的总销售额

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而且只有两张桌子可供使用

订单\产品：订单\标识、产品\标识、产品\名称

订单：订单号、客户号、购买日期

我以为左键连接两个表会让我对未购买的项目充满空值。。。但它只提供了购买物品的行。如何计算所有已购买/未购买项目的每次总销售额

*更新

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首先，您应该使用

左外连接

。您的

WHERE

子句正在减少您的结果。您应该将其删除为您的

WHERE

子句，或者添加如下内容：

SELECT 
op.products_name,
ROUND(SUM( IF(MONTH(o.date_purchased) = 1, op.final_price * op.products_quantity,0)), 2) AS january,
ROUND(SUM( IF(MONTH(o.date_purchased) = 2, op.final_price * op.products_quantity,0)), 2) AS febraury,
ROUND(SUM( IF(MONTH(o.date_purchased) = 3, op.final_price * op.products_quantity,0)), 2) AS march,
ROUND(SUM( IF(MONTH(o.date_purchased) = 4, op.final_price * op.products_quantity,0)), 2) AS april,
ROUND(SUM( IF(MONTH(o.date_purchased) = 5, op.final_price * op.products_quantity,0)), 2) AS may,
ROUND(SUM( IF(MONTH(o.date_purchased) = 6, op.final_price * op.products_quantity,0)), 2) AS june,
ROUND(SUM( IF(MONTH(o.date_purchased) = 7, op.final_price * op.products_quantity,0)), 2) AS july,
ROUND(SUM( IF(MONTH(o.date_purchased) = 8, op.final_price * op.products_quantity,0)), 2) AS august,
ROUND(SUM( IF(MONTH(o.date_purchased) = 9, op.final_price * op.products_quantity,0)), 2) AS september,
ROUND(SUM( IF(MONTH(o.date_purchased) = 10, op.final_price * op.products_quantity,0)), 2) AS october,
ROUND(SUM( IF(MONTH(o.date_purchased) = 11, op.final_price * op.products_quantity,0)), 2) AS november,
ROUND(SUM( IF(MONTH(o.date_purchased) = 12, op.final_price * op.products_quantity,0)), 2) AS december
FROM orders_products op
LEFT OUTER JOIN orders o ON op.orders_id = o.orders_id
WHERE (customers_id = 31 
AND YEAR(o.date_purchased) = 2014) 
OR o.date_purchased IS NULL
GROUP BY op.products_id
ORDER BY op.products_name

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请提供样本数据和预期输出您是否也有

产品

表？

orders\u products

表的

products\u id

字段是否引用了该表？能否请您发布表格数据的示例（包括

产品

，如果存在）？@fathahrhmanp I包括一个exmaple。谢谢。@PeterWiggin希望我的示例这次能给您提供清晰的信息：）谢谢。您确定带有

蛋白质

的行中有

产品\u id=30

？唯一的

产品\u名称

是否对应于唯一的

产品\u id

？这真奇怪！既然我已经确认它正在sqlfiddle上工作，我将接受这个答案，并将在我的问题上做更多的工作。谢谢

SELECT 
op.products_name,
ROUND(SUM( IF(MONTH(o.date_purchased) = 1, op.final_price * op.products_quantity,0)), 2) AS january,
ROUND(SUM( IF(MONTH(o.date_purchased) = 2, op.final_price * op.products_quantity,0)), 2) AS febraury,
ROUND(SUM( IF(MONTH(o.date_purchased) = 3, op.final_price * op.products_quantity,0)), 2) AS march,
ROUND(SUM( IF(MONTH(o.date_purchased) = 4, op.final_price * op.products_quantity,0)), 2) AS april,
ROUND(SUM( IF(MONTH(o.date_purchased) = 5, op.final_price * op.products_quantity,0)), 2) AS may,
ROUND(SUM( IF(MONTH(o.date_purchased) = 6, op.final_price * op.products_quantity,0)), 2) AS june,
ROUND(SUM( IF(MONTH(o.date_purchased) = 7, op.final_price * op.products_quantity,0)), 2) AS july,
ROUND(SUM( IF(MONTH(o.date_purchased) = 8, op.final_price * op.products_quantity,0)), 2) AS august,
ROUND(SUM( IF(MONTH(o.date_purchased) = 9, op.final_price * op.products_quantity,0)), 2) AS september,
ROUND(SUM( IF(MONTH(o.date_purchased) = 10, op.final_price * op.products_quantity,0)), 2) AS october,
ROUND(SUM( IF(MONTH(o.date_purchased) = 11, op.final_price * op.products_quantity,0)), 2) AS november,
ROUND(SUM( IF(MONTH(o.date_purchased) = 12, op.final_price * op.products_quantity,0)), 2) AS december
FROM orders_products op
LEFT OUTER JOIN orders o ON op.orders_id = o.orders_id
WHERE (customers_id = 31 
AND YEAR(o.date_purchased) = 2014) 
OR o.date_purchased IS NULL
GROUP BY op.products_id
ORDER BY op.products_name