只是在oracle的环境下进行的几个数的测试,在这里只是举例说明,没有理论说明,抱歉. select ceil(1.8) from dual; --结果为1,向上取整select floor (1.8) from dual;--结果为2,向上取整select trunc(1.999333,1) from dual; --结果为1.9,根据精度(1自身设置)取值,取值不舍入select round(1.8992,3) from dual;--结果为1.899,根据精度取值,取值舍入select s…