mysql中运算符的使用示例-创新互联
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案例：创建数据表tmp15，其中包含varchar类型的字段note和int类型的字段price。
使用运算符对表tmp15中不同的字段进行运算。
使用逻辑操作符对数据进行逻辑操作。
使用位操作符对数据进行位操作。
首先创建tmp15表，插入一条记录，note值为"Thisisgood"，price值为50，SQL语句如下：
mysql> create table tmp15 -> (
-> note varchar(100),
-> price int
-> );Query OK, 0 rows affected (0.13 sec)mysql> into tmp15 values
-> (
-> "Thisisgood",50
-> );
mysql> insert into tmp15 values
-> ("Thisisgood",50);Query OK, 1 row affected (0.06 sec)(1)对表tmp15中的整型数值字段price进行算数运算，SQL语句如下：
mysql> select price, -> price + 10, -> price - 10, -> price * 2, -> price / 2, -> price % 3 -> from tmp15;+-------+------------+------------+-----------+-----------+-----------+| price | price + 10 | price - 10 | price * 2 | price / 2 | price % 3 |+-------+------------+------------+-----------+-----------+-----------+| 50 | 60 | 40 | 100 | 25.0000 | 2 |+-------+------------+------------+-----------+-----------+-----------+1 row in set (0.00 sec)
(2)对表tmp15中的整型数值字段price进行比较运算，SQL语句如下：
mysql> select price, -> price>10, -> price<10, -> price != 10, -> price = 10, -> price<=>10, -> price<>10 -> from tmp15;+-------+----------+----------+-------------+------------+------------+-----------+| price | price>10 | price<10 | price != 10 | price = 10 | price<=>10 | price<>10 |+-------+----------+----------+-------------+------------+------------+-----------+| 50 | 1 | 0 | 1 | 0 | 0 | 1 |+-------+----------+----------+-------------+------------+------------+-----------+1 row in set (0.00 sec)
(3)判断price值是否落在30—80区间、返回70、30相比较大的值、判断price是否为in列表(10、20、50、35)中的某个值，SQL语句如下：
mysql> select price, -> price between 30 and 80, -> greatest(price,70,30), -> price in(10,20,50,35) -> from tmp15;+-------+-------------------------+-----------------------+-----------------------+| price | price between 30 and 80 | greatest(price,70,30) | price in(10,20,50,35) |+-------+-------------------------+-----------------------+-----------------------+| 50 | 1 | 70 | 1 |+-------+-------------------------+-----------------------+-----------------------+1 row in set (0.00 sec)
(4)对tmp15中的字符串数值字段note进行比较运算，判断表tmp15中note字段是否为空、使用LIKE判断是否以字母"t"开头、使用regexp判断是否以字母“y”结尾、判断是否包含字母“g”或者“m”，SQL语句如下：
mysql> select note, -> note is null, -> note like 't%', -> note regexp '$y', -> note regexp '[gm]' -> from tmp15;+------------+--------------+----------------+------------------+--------------------+| note | note is null | note like 't%' | note regexp '$y' | note regexp '[gm]' |+------------+--------------+----------------+------------------+--------------------+| Thisisgood | 0 | 1 | 0 | 1 |+------------+--------------+----------------+------------------+--------------------+1 row in set (0.05 sec)
(5)将price字段值与null、0进行逻辑运算，SQL语句如下：
mysql> select price, -> price && 1, -> price && null, -> price || 0, -> price and 0, -> 0 and null, -> price or null -> from tmp15;+-------+------------+---------------+------------+-------------+------------+---------------+| price | price && 1 | price && null | price || 0 | price and 0 | 0 and null | price or null |+-------+------------+---------------+------------+-------------+------------+---------------+| 50 | 1 | NULL | 1 | 0 | 0 | 1 |+-------+------------+---------------+------------+-------------+------------+---------------+1 row in set (0.00 sec)mysql> select price, -> !price, -> not null, -> price xor 3, -> 0 xor null, -> price xor 0 -> from tmp15;+-------+--------+----------+-------------+------------+-------------+| price | !price | not null | price xor 3 | 0 xor null | price xor 0 |+-------+--------+----------+-------------+------------+-------------+| 50 | 0 | NULL | 0 | NULL | 1 |+-------+--------+----------+-------------+------------+-------------+1 row in set (0.00 sec)
(6)将price字段值与2、4进行按位与、按位或 操作，并对price进行按位操作，SQL语句如下：
mysql> select price, -> price & 2, -> price | 4, -> ~price from tmp15;+-------+-----------+-----------+----------------------+| price | price & 2 | price | 4 | ~price |+-------+-----------+-----------+----------------------+| 50 | 2 | 54 | 18446744073709551565 |+-------+-----------+-----------+----------------------+1 row in set (0.00 sec)
(7)将price字段值分别额左移和右移两位，SQL语句如下：
mysql> select price, -> price<<2, -> price>>2 -> from tmp15;+-------+----------+----------+| price | price<<2 | price>>2 |+-------+----------+----------+| 50 | 200 | 12 |+-------+----------+----------+1 row in set (0.00 sec)
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