通过唯一关键字和在列中添加总计来连接两个 Mysql 表答案

【问题标题】：Join two Mysql tables by unique keywords and by adding total in column通过唯一关键字和在列中添加总计来连接两个 Mysql 表
【发布时间】：2013-05-21 11:20:06
【问题描述】：

我正在尝试将每个位置的每日总数放到另一个表中。

结构如下：

reports_location_temp：

Table_Name:           Date:                              Total_Count:
London                2013-05-26 10:49:53                5000
London                2013-05-26 10:49:53                2000
Birmingham            2013-05-26 10:49:53                1000
London                2013-05-26 10:49:53                5000
Manchester            2013-05-26 10:49:53                50
Birmingham            2013-05-26 10:49:53                500

reports_location_total_daily：

Table_Name:           Date:                              Total_Count:
London                2013-05-26 23:55:00                12000
Manchester            2013-05-26 23:55:00                50
Birmingham            2013-05-26 23:55:00                1500

我仍在学习 Mysql。

这是我尝试过的查询，但它只为每个 Unique Table_Name 选择一列：

UPDATE reports_Location_total_daily j1 INNER JOIN reports_location_temp l1 ON j1.Table_Name = l1.Table_Name SET j1.Total_Count = l1.Total_Count

感谢您对此的帮助。

【问题讨论】：

为什么不写2个请求：从第一个中选择，按Table_Name分组并更新第二个表？
调查命令insert into . . . on duplicate key。

标签： mysql sql inner-join outer-join

【解决方案1】：

CREATE TABLE sales
(id INT NOT NULL AUTO_INCREMENT,
location VARCHAR(40), 
today DATETIME NOT NULL,
sales INT NOT NULL,
PRIMARY KEY (id)
)
;


INSERT sales (location,today,sales) VALUES ('London','2013-05-26',2000);
INSERT sales (location,today,sales) VALUES ('Birm','2013-05-26',1000);
INSERT sales (location,today,sales) VALUES ('London','2013-05-26',1500);
INSERT sales (location,today,sales) VALUES ('London','2013-05-24',100);
INSERT sales (location,today,sales) VALUES ('Birm','2013-05-24',200);
INSERT sales (location,today,sales) VALUES ('London','2013-05-24',300);

CREATE TABLE daily_totals
(id INT NOT NULL AUTO_INCREMENT,
location VARCHAR(40), 
today DATETIME NOT NULL,
totalsales INT NOT NULL,
PRIMARY KEY (id)
)
;

DELETE FROM daily_totals;

INSERT INTO daily_totals (location,today,totalsales)
SELECT location,
DATE(today),
SUM(sales)
FROM sales
GROUP BY location,DATE(today)

【讨论】：