我们可以使用数学运算对 MySQL 结果进行排序吗?\
mysqlmysqli database
是的，我们可以使用 ORDER BY 子句通过数学运算进行排序。让我们首先创建一个表:
mysql> create table orderByMathCalculation -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Quantity int, -> Price int -> ); Query OK, 0 rows affected (0.57 sec)
下面是使用 insert 命令在表中插入一些记录的查询:
mysql> insert into orderByMathCalculation(Quantity,Price) values(10,50); Query OK, 1 row affected (0.21 sec) mysql> insert into orderByMathCalculation(Quantity,Price) values(20,40); Query OK, 1 row affected (0.14 sec) mysql> insert into orderByMathCalculation(Quantity,Price) values(2,20); Query OK, 1 row affected (0.13 sec) mysql> insert into orderByMathCalculation(Quantity,Price) values(11,10); Query OK, 1 row affected (0.24 sec)
以下是使用 select 语句显示表中的所有记录的查询:
mysql> select *from orderByMathCalculation;
这将产生以下输出
+----+----------+-------+ | Id | Quantity | Price | +----+----------+-------+ | 1 | 10 | 50 | | 2 | 20 | 40 | | 3 | 2 | 20 | | 4 | 11 | 10 | +----+----------+-------+ 4 rows in set (0.00 sec)
案例 1:这是按升序按数学运算进行排序的查询。
mysql> select *from orderByMathCalculation order by Quantity*Price;
这将产生以下输出
+----+----------+-------+ | Id | Quantity | Price | +----+----------+-------+ | 3 | 2 | 20 | | 4 | 11 | 10 | | 1 | 10 | 50 | | 2 | 20 | 40 | +----+----------+-------+ 4 rows in set (0.00 sec)
案例 2:这是按降序进行数学运算排序的查询。
mysql> select *from orderByMathCalculation order by Quantity*Price desc;
这将产生以下输出
+----+----------+-------+ | Id | Quantity | Price | +----+----------+-------+ | 2 | 20 | 40 | | 1 | 10 | 50 | | 4 | 11 | 10 | | 3 | 2 | 20 | +----+----------+-------+ 4 rows in set (0.00 sec)
