Question

我希望我可以更改架构，但我与之相关，假设我有以下表格

JanDataTable
FebDataTable
MarDataTable
ProductsTable

前三个表格中有列ID和已售出金额。产品表有ID和产品名称。

我需要以某种方式连接这些表以获得以下输出

ID | Product Name | Amount Sold | Month 
01 | TV 1         | 23          | 1     <- JanDataTable
02 | TV 2         | 43          | 2     <- FebDataTable
03 | Toaster 1    | 72          | 3     <- MarDataTable

ID是产品ID。

只是一个查询吗？

Answer 1

这个怎么样？

使用LEFT JOIN执行此操作。

select 
    p.id as ID, p.`Product Name`,
    coalesce(jan.`Amount Sold`,0) + coalesce(feb.`Amount Sold`,0) + coalesce(mar.`Amount Sold`,0) as `Amount Sold`,
    case when p.id = '01' then 1
        when p.id = '02' then 2
        when p.id = '03' thwn 3
    end as Month
from ProductsTable as p
    LEFT JOIN JanDataTable as jan ON p.id = jan.id 
    LEFT JOIN FebDataTable as feb ON p.id = feb.id 
    LEFT JOIN MarDataTable as mar ON p.id = mar.id

Answer 2

select p.product_part,s.*
from
(
select d.*, 1 as Month from jandatatable d
union
select d.*, 2 as Month from febdatatable d
union
select d.*, 3 as Month from mardatatable d
) s
join product p on s.Product_id = p.product_id
order by s.month, p.product_id;

透视MySQL数据

2 个答案: