MySQL 帮助进行查询

Question

我需要显示 6 个月的产品消耗情况。

我的表消耗如下:

int ID_Conso
int ID_Product
int Quantity_Conso
int Month_Conso
int Year_COnso

如下图所示，有 1 条记录/1 个产品/1 个月

我想为我的 View 编写的查询必须将结果显示为:

这是我的查询:

      SELECT c.id_Product,
         t1.conso1, 
         t2.conso2, 
         t3.conso3, 
         t4.conso4, 
         t5.conso5, 
         t6.conso6
  FROM Consumption c,
     (SELECT quantity_conso as "conso1" 
            FROM `consumption` 
            WHERE year= Year(Now()) and month = 1) t1,
     (SELECT quantity_conso as "conso2" 
            FROM `consumption` 
            WHERE year= Year(Now()) and month = 2) t2,
     (SELECT quantity_conso as "conso3" 
            FROM `consumption` 
            WHERE year= Year(Now()) and month = 3) t3,
     (SELECT quantity_conso as "conso4" 
            FROM `consumption` 
            WHERE year= Year(Now()) and month = 4) t4,
     (SELECT quantity_conso as "conso5" 
            FROM `consumption` 
            WHERE year= Year(Now()) and month = 5) t5,
     (SELECT quantity_conso as "conso6" 
            FROM `consumption` 
            WHERE year= Year(Now()) and month = 6) t6

此查询显示所有 id_product 的所有记录(如果缺少一条记录，则不会显示 null)

我尝试过使用ifexit，但没有成功。

Answer 1

使用聚合函数SUM与 IF ，以及 Id_Product 上的 GROUP BY。尝试以下查询:

SELECT 
  Id_Product, 
  SUM(IF(Month_Conso = 1, Quantity_Conso, 0)) AS QtyConso_Month1, 
  SUM(IF(Month_Conso = 2, Quantity_Conso, 0)) AS QtyConso_Month2, 
  SUM(IF(Month_Conso = 3, Quantity_Conso, 0)) AS QtyConso_Month3, 
  SUM(IF(Month_Conso = 4, Quantity_Conso, 0)) AS QtyConso_Month4, 
  SUM(IF(Month_Conso = 5, Quantity_Conso, 0)) AS QtyConso_Month5, 
  SUM(IF(Month_Conso = 6, Quantity_Conso, 0)) AS QtyConso_Month6 
FROM Consumption 
GROUP BY Id_Product 
ORDER BY Id_Product ASC