一 ROUND（number[,fmt]）

     ：四舍五入，默认取整；

          round(123.456)  即 round(123.456,0)  = 123

         round(123.456,1)   = 123.5

         round(123.456,2)   = 123.46

         round(123.456,3)   = 123.456

         round(123.456,-1)  = round(-123.456,-1)  = 120

         round(123.456,-2)  = round(123.456,-2)   = 100

         round(123.456,-3)  = round(123.456,-3)   = 0

二 TRUNC（number,[,fmt]）

      ：截取，

       trunc(123.456,0)  即  trunc(123.456,0)  = 123

       trunc(123.456,1)   = 123.4

       trunc(123.456,2)   = 123.45

       trunc(123.456,-1)  = 120

       trunc(123.456,-2)  = 100

       trunc(-123.456,0)  = -123

       trunc(-123.456,-1) = -120

       trunc(-123.456,-2)  = -100

       trunc(-123.456,-3) = 0

      注：TRUNC()还可以截取日期哦。