SQL 从查询结果里查询

感悟时分

有orders表：


我想要从从表中查出每天电动车和手机各自的销售总额。这个需求还是蛮简单的，只需要根据createtime和pro
duct group by就行了。下面是我写的SQL语句：

SELECT DATE_FORMAT( createtime, "%Y-%m-%d" ) cr, product, SUM(price) total FROM orders GROUP BY
DATE_FORMAT(createtime, "%Y-%m-%d"), product
1
查询结果如下：


这个结果确实满足了我的需求，但是存在一个问题，就是当天数多了的时候，会看得我头晕眼花的。如果查
询结果是下面这个样子，我想看起来会舒服得多：

对于如何直接从表中查询出这样的结果，我是一点想法都没有，但是，我却知道如何从上一个SQL语句的
查询结果中查询从而得到想要的结果，下面是我写的SQL语句：

1. 
   
2. SELECT origintable.cr,
   
3. SUM(CASE WHEN origintable.product = "电动车" THEN origintable.total ELSE 0 END) "电动车",
   
4. SUM(CASE WHEN origintable.product = "手机" THEN origintable.total ELSE 0 END) "手机"
   
5. FROM (SELECT DATE_FORMAT( createtime, "%Y-%m-%d" ) AS cr, product, SUM(price) AS total
   
6. FROM orders GROUP BY DATE_FORMAT(createtime, "%Y-%m-%d"), product) AS origintable
   
7. GROUP BY origintable.cr

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如果大家想亲自试一试，可以用下面的SQL语句创建orders表和向表中插入数据：

1. 
   
2. create table orders(
   
3. id int PRIMARY KEY auto_increment,
   
4. product VARCHAR(64) null,
   
5. price DOUBLE null,
   
6. createtime DATETIME
   
7. )
   
8. 
   
9. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("电动车", 50, NOW());
   
10. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("手机", 60, NOW());
    
11. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("电动车", 50, NOW());
    
12. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("手机", 60, NOW());
    
13. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("电动车", 50, "2016-04-14 22:16:11");
    
14. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("手机", 60, "2016-04-14 22:16:11");
    
15. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("电动车", 50, "2016-04-14 22:16:11");
    
16. INSERT INTO orders (orders.product, orders.price, orders.createtime) VALUES ("手机", 60, "2016-04-14 22:16:11");
    

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如果大家有其它方式实现本文的需求，欢迎留言。

提示：
本文所有SQL语句均根据MySQL数据库编写。

chenyangyang1

正在了解

Ta因为帅居然

select create_time,sum(if(product ='电动车',price,0))as '电动车当日销售额'，sum(if(product ='手机',price,0))as '当日手机销售额'from table group by create_time

testing444555

jinsolo823

select createtime,sum(if(product ='电动车',price,0))as '电动车当日销售额',sum(if(product ='手机',price,0))as '当日手机销售额'from orders group by createtime;

RedQA

哦