数学函数

ABS(n)

返回n的绝对值

示例

FLOOR(n)

返回不大于n的最大整数值

示例

mysql> select reverse('CDA');

+----------------+

| reverse('CDA') |

+----------------+

| ADC |

+----------------+

mysql> select upper('cda');

+--------------+

| upper('cda') |

+--------------+

| CDA |

+--------------+

mysql> select lower('CDA');

+-----------------+

| lower('CDA') |+-------------- --+| cda |

+-----------------+

mysql> select abs(-32);

+----------+

| abs(-32) |

+----------+

| 32 |

+----------+

CEILING(n)

返回不小于n的最小整数值

示例

ROUND(n[,d])

返回n的四舍五入值,保留d位小数(d的默认值为0)

示例

RAND([n])

返回在范围0到1.0内的随机浮点值(可以使用数字n作为初始值)

示例

时期时间函数

DATE(date)

返回指定日期/时间表达式的日期部分或将文本转为日期格式

mysql> select floor(1.23);

+-------------+

| floor(1.23) |

+-------------+

| 1 |

+-------------+

mysql> select ceiling(1.23);

+---------------+

| ceiling(1.23) |

+---------------+

| 2 |

+---------------+

mysql> select round(1.58);

+-------------+

| round(1.58) |

+-------------+

| 2 |

+-------------+

mysql> select rand();

+--------------------+

| rand() |

+--------------------+

| 0.8111234054072978 |

+--------------------+

mysql> select rand(2);

+--------------------+

| rand(2) |

+--------------------+

| 0.6555866465490187 |

+--------------------+