1. 向下取整
例如:
select floor(123.95689) from dual 结果:123
select floor(123.35689) from dual 结果:123
2.向上取整 例如:
select ceil(123.95689) from dual 结果:124
select ceil(123.15689) from dual 结果:124
3.四舍五入保留n位小数:
select round(123.55689,0) from dual 结果:124
select round(123.45689,0) from dual 结果:123
select round(123.55689) from dual 结果:123 也就是说,如果不保留小数位数,可以直接写数值
select round(123.55689,2) from dual 结果:123.56
select round(123.55649,3) from dual 结果:123.556
4.不是四舍五入,直接摄取若干小数位:
select trunc(123.55689,3) from dual 结果:123.556
select trunc(123.55689,0) from dual 结果:123
select trunc(123.55689) from dual 结果:123