MySQL_关于用嵌套表计算的可以不用 20161205

计算求和类的指标,其实用不到嵌套表，比如计算各城市产品分类的订单额。

如果要计算不重复的指标 比如一个用户一天下了多个订单 用这样的表计算一天有多少用户下单 这个用户肯定是去重的 下多个订单也应该视为一个用户

这个用嵌套表主要是为了逻辑理解清楚 一步步来,如果对数据库表很熟悉的话可以省去嵌套表的步骤

1、嵌套表

##C024_02 上周品类销售收入
SELECT  CONCAT(b.分类ID,'-',a.产品分类) AS 商品分类
,SUM(IF(城市="城市A",销售确认额,NULL)) AS 城市A,SUM(IF(城市="城市B",销售确认额,NULL)) AS 城市B,SUM(IF(城市="城市C",销售确认额,NULL)) AS 城市C
,SUM(IF(城市="城市D",销售确认额,NULL)) AS 城市D,SUM(IF(城市="城市E",销售确认额,NULL)) AS 城市E
FROM (#上周一到本周一
    SELECT 城市,a2.产品分类,SUM(销售额) AS 销售确认额
    FROM `a005_account` AS a1
    LEFT JOIN `a002_产品` AS a2 ON a1.产品ID=a2.产品ID
    WHERE 应收日>=DATE_ADD(DATE(DATE_ADD(CURRENT_DATE,INTERVAL -WEEKDAY(CURRENT_DATE) DAY)),INTERVAL -1 WEEK) AND 应收日<DATE(DATE_ADD(CURRENT_DATE,INTERVAL -WEEKDAY(CURRENT_DATE) DAY))
    GROUP BY 城市,a2.产品分类
) AS a
LEFT JOIN `a000_cate` AS b ON a.产品分类=b.产品分类
GROUP BY a.产品分类
ORDER BY b.分类ID

　2、不用嵌套

##C024_02 上周品类销售收入
SELECT  CONCAT(a3.分类ID,'-',a2.产品分类) AS 商品分类
,SUM(IF(城市="城市A",销售额,NULL)) AS 城市A,SUM(IF(城市="城市B",销售额,NULL)) AS 城市B,SUM(IF(城市="城市C",销售额,NULL)) AS 城市C
,SUM(IF(城市="城市D",销售额,NULL)) AS 城市D,SUM(IF(城市="城市E",销售额,NULL)) AS 城市E
FROM `a005_account` AS a1
LEFT JOIN `a002_产品` AS a2 ON a1.产品ID=a2.产品ID
LEFT JOIN `a000_cate` AS a3 ON a2.产品分类=a3.产品分类
WHERE 应收日>=DATE_ADD(DATE(DATE_ADD(CURRENT_DATE,INTERVAL -WEEKDAY(CURRENT_DATE) DAY)),INTERVAL -1 WEEK) AND 应收日<DATE(DATE_ADD(CURRENT_DATE,INTERVAL -WEEKDAY(CURRENT_DATE) DAY))
GROUP BY a2.产品分类
ORDER BY a3.分类ID