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这篇文章将为大家详细讲解有关 mysql 中运算符的使用示例,丸趣 TV 小编觉得挺实用的,因此分享给大家做个参考,希望大家阅读完这篇文章后可以有所收获。
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 相比最大的值、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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