## 数学函数 abs()：绝对值 ceiling()：向上取整 floor()：向下取整 pow()：求指数，谁的多少次方 rand()：获取一个随机数（0-1之间） round()：四舍五入函数 ~~~ select abs(-1),ceiling(4.5),floor(4.4),pow(2,8),rand(),round(1.5); ~~~ 结果 ~~~ +---------+--------------+------------+----------+--------------------+------------+ | abs(-1) | ceiling(4.5) | floor(4.4) | pow(2,8) | rand() | round(1.5) | +---------+--------------+------------+----------+--------------------+------------+ | 1 | 5 | 4 | 256 | 0.6159026330485033 | 2 | +---------+--------------+------------+----------+--------------------+------------+ ~~~