oracle处理小数点位数取四舍五入,或只保留小数不进位

1.取四舍五入的几位小数
               eg:            
                         round(n+0.{m个0}5, m)

                                      比如， 取两位的话:
                                      round(15.333 + 0.005, 2)
2. 只保留小数
                eg:
                                       保留两位小数，只舍
              SQL>        select trunc(1.2345, 2) from dual;

                                       TRUNC(1.2345,2)
                                       ---------------
                                       1.23

               SQL>        select trunc(1.2399, 2) from dual;

                                        TRUNC(1.2399,2)
                                        ---------------
                                       1.23
3.这个比较全了
返回大于或等于x的最大整数:   
       SQL>        select        ceil(23.33)        from        dual;   
    
       CEIL(23.33)   
       -----------   
                         24   
    
       返回等于或小于x的最大整数:   
       SQL>        select        floor(23.33)        from        dual;   
    
       FLOOR(23.33)   
       ------------   
                           23   
    
       返回舍入到小数点右边y位的x值:rcund(x,[y])   
       SQL>        select        round(23.33)        from        dual;   
    
       ROUND(23.33)   
       ------------   
                           23   
    
       返回截尾到y位小数的x值:trunc(x,[y])   
       SQL>        select        trunc(23.33)        from        dual;   
    
       TRUNC(23.33)   
       ------------   
  
                         23