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法律研究从 MySQL 表中选择并相加两列相乘的结果？
你可以使用聚合函数 SUM()。我们首先创建一个表 -
mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, CustomerProductName varchar(100), CustomerProductQuantity int, CustomerPrice int ); Query OK, 0 rows affected (0.17 sec)
使用 insert 命令在表中插入一些记录 -
mysql> insert into DemoTable(CustomerProductName,CustomerProductQuantity,CustomerPrice) values('Product-1',5,400); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(CustomerProductName,CustomerProductQuantity,CustomerPrice) values('Product-2',3,100); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(CustomerProductName,CustomerProductQuantity,CustomerPrice) values('Product-1',2,300); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(CustomerProductName,CustomerProductQuantity,CustomerPrice) values('Product-1',5,50); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable(CustomerProductName,CustomerProductQuantity,CustomerPrice) values('Product-3',6,10); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable(CustomerProductName,CustomerProductQuantity,CustomerPrice) values('Product-2',10,20); Query OK, 1 row affected (0.03 sec)
使用 select 语句显示表中的所有记录 -
mysql> select *from DemoTable;
这将产生以下输出 -
+------------+---------------------+-------------------------+---------------+ | CustomerId | CustomerProductName | CustomerProductQuantity | CustomerPrice | +------------+---------------------+-------------------------+---------------+ | 1 | Product-1 | 5 | 400 | | 2 | Product-2 | 3 | 100 | | 3 | Product-1 | 2 | 300 | | 4 | Product-1 | 5 | 50 | | 5 | Product-3 | 6 | 10 | | 6 | Product-2 | 10 | 20 | +------------+---------------------+-------------------------+---------------+ 6 rows in set (0.00 sec)
以下是从 MySQL 表中选择和相加两列 (CustomerProductQuantity*CustomerPrice) 乘积结果的查询。
mysql> select CustomerProductName, SUM(CustomerProductQuantity*CustomerPrice) AS TOTAL_PRICE from DemoTable group by CustomerProductName;
这将产生以下输出 -
+---------------------+-------------+ | CustomerProductName | TOTAL_PRICE | +---------------------+-------------+ | Product-1 | 2850 | | Product-2 | 500 | | Product-3 | 60 | +---------------------+-------------+ 3 rows in set (0.00 sec)
更新于： 30-7-2019
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