MySQL排序_20160926

在工作中对数据进行排序也是最常用的,比如根据用户的下单金额降序 或者对销售业绩进行降序排序 在考核员工KPI时候也经常用到

一、order  by 函数

order by 函数默认根据后面字段升序，使用降序使用

order by 字段名 desc写法

计算各城市各产品3个月份分别的订单额,以9月金额降序

 SELECT city,productID,productname,SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201607,pay_money,NULL)) AS 7月金额,
 SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201608,pay_money,NULL)) AS 8月金额,
 SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201609,pay_money,NULL)) AS 9月金额
 FROM test_a03order
 GROUP BY city,productID
 ORDER BY SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201609,pay_money,NULL)) DESC

2、order by field（）函数 自定义排序

类似于excel中自定义排序一样 mysql也支持根据字段自定义排序

2.1SQL 让城市以city_A,city_C,city_B,city_D,city_E 这样的排序  

对比2.2SQL  2.1SQL field 函数里面没有把city_F放到自定义顺序里面 结果city_F默认置前 这个在以后with rollup函数会用到

 SELECT city,productID,productname,SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201607,pay_money,NULL)) AS 7月金额,
 SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201608,pay_money,NULL)) AS 8月金额,
 SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201609,pay_money,NULL)) AS 9月金额
 FROM test_a03order
 GROUP BY city,productID
 ORDER BY FIELD(city,"city_A","city_C","city_B","city_D","city_E")

2.2 SQL  field 函数里面把city_F放到自定义顺序里面 city_F置于最后

 SELECT city,productID,productname,SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201607,pay_money,NULL)) AS 7月金额,
 SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201608,pay_money,NULL)) AS 8月金额,
 SUM(IF(DATE_FORMAT(order_date,"%Y%m")=201609,pay_money,NULL)) AS 9月金额
 FROM test_a03order
 GROUP BY city,productID
 ORDER BY FIELD(city,"city_A","city_C","city_B","city_D","city_E","city_F")