1、首先观察两个表的格式

表1、销售明细

 

表2、产品明细

2、在mysql中新建表

表1：订单明细表 sales

sql如下

CREATE TABLE sales  (
  `产品ID` int NOT NULL,
	  `销售数量` int(20) ,
  `销售时间` timestamp(6) NULL DEFAULT NULL,
  PRIMARY KEY (`订单ID`) 
)
INSERT INTO sales VALUES ('C1001', 15, '2020-06-01 10:10:12');
INSERT INTO sales VALUES ('C1002',26, '2020-05-02 0:10:12');
INSERT INTO sales VALUES ('C1003', 21, '2020-04-03 0:10:12');
INSERT INTO sales VALUES ('C1003', 23, '2020-04-04 0:10:12');
INSERT INTO sales VALUES ('C1003', 0, '2020-03-05 0:10:12');
INSERT INTO sales VALUES ('C1001', 16, '2020-02-06 3:0:12');
INSERT INTO sales VALUES ('C1002', 32, '2020-01-07 0:10:12');
INSERT INTO sales VALUES ('C1001', 16, '2019-12-08 0:12:24');
INSERT INTO sales VALUES ('C1001', 32, '2019-06-09  0:12:24');
INSERT INTO sales VALUES ('C1002', 17, '2019-05-09 0:12:24');

数据预览：

 

表2：产品表 product

sql 如下：

CREATE TABLE product  (
  `产品ID` varchar(20) NOT NULL,
	  `产品名称` varchar(20) ,
  `产品单价` int (10)
)
INSERT INTO product VALUES ('C1001','产品A',45);
INSERT INTO product VALUES ('C1002','产品B',52);
INSERT INTO product VALUES ('C1003','产品C',39);

预览

3、计算同比环比

sql如下：

select  year(c.销售时间) yy,month(c.销售时间) mm,     
       sum(c.销售数量*d.产品单价) ss,
concat(ifnull(abs(round((sum(c.销售数量*d.产品单价)-ss1)/ss1*100,2)),0),'%') 同比,
concat(ifnull(abs(round((sum(c.销售数量*d.产品单价)-ss2)/ss2*100,2)),0),'%')  环比
from sales c
left join product d on c.产品ID=d.产品ID
left join (select month(a.销售时间) mm1,
                    year(a.销售时间) yy1,
                    sum(a.销售数量*d.产品单价) ss1
          from sales a
          left join product d on a.产品ID=d.产品ID
          GROUP BY mm1,yy1) a
          on month(c.销售时间) = a.mm1 
          and a.yy1 = year(c.销售时间)-1	 
 left join  (select month(a.销售时间) mm2,
                    year(a.销售时间) yy2,
                    sum(a.销售数量*d.产品单价) ss2
             from sales a
		     left join product d on a.产品ID=d.产品ID
              GROUP BY mm2,yy2) b
on (b.yy2 = year(c.销售时间) and b.mm2+1 = month(c.销售时间) OR (yy2=year(c.销售时间)-1 
AND b.mm2 = 12 AND month(c.销售时间) = 1))
 group by yy, mm
 order by yy,mm asc

sql解析：

select  year(c.销售时间) yy,month(c.销售时间) mm,     
       sum(c.销售数量*d.产品单价) ss,

# concat函数，mysql字符串拼接，因为同比和环比都是百分数
# ifnull函数，mysql判断字段是否为空，为空则为0
# abs函数,mysql取绝对值，因为我这里取的都是正数
# round函数，mysql保留几位小数
concat(ifnull(abs(round((sum(c.销售数量*d.产品单价)-ss1)/ss1*100,2)),0),'%') 同比,
concat(ifnull(abs(round((sum(c.销售数量*d.产品单价)-ss2)/ss2*100,2)),0),'%')  环比
from sales c
left join product d on c.产品ID=d.产品ID

# 上一年销售额
left join (select month(a.销售时间) mm1,
                    year(a.销售时间) yy1,
                    sum(a.销售数量*d.产品单价) ss1
          from sales a
          left join product d on a.产品ID=d.产品ID
          GROUP BY mm1,yy1) a
          # 同比月份相同，年份减1
          on month(c.销售时间) = a.mm1   
          and a.yy1 = year(c.销售时间)-1	

# 今年销售额 
 left join  (select month(a.销售时间) mm2,
                    year(a.销售时间) yy2,
                    sum(a.销售数量*d.产品单价) ss2
             from sales a
		     left join product d on a.产品ID=d.产品ID
              GROUP BY mm2,yy2) b
          # 环比取数考虑到为一月的情况
on (b.yy2 = year(c.销售时间) and b.mm2+1 = month(c.销售时间) OR (yy2=year(c.销售时间)-1 
AND b.mm2 = 12 AND month(c.销售时间) = 1))
 group by yy, mm
 order by yy,mm asc

 运行结果如下：

结果测试：

温馨提示：

   由于mysql在规则上和函数上与Oracle等也有些差异，列如：函数、大小写、别名的情况都可能导致出现sql执行的结果出现问题，所以在套用的时候需要细心一点。

除此之外，还要计算累计销售

sql如下：

select year(销售时间) yy,month(销售时间) mm,
sum(销售数量*b.产品单价) over(order by year(销售时间) ,month(销售时间) ) 累计数量 
from sales a
left join product b on a.产品ID=b.产品ID
order by  yy,mm

   查看了一些资料，感觉环比同比还是不太好写，今天总结整理一下。