internal table max,min for particular value

Hi all,

I need to select max and min value from an internal table.

the internal table values are

objectid     value_new      value_old

   290               1                     25

   290               17                    1

   291               768                 50

   291              100000          768 

   341               15                    0

my output should be

objectid     value_new     value_old

290               17                    1

291               100000            50

341               15                    0

(i.e) for objectid 290, value-new should be maximum value and value_old should be minimum value.

Pls give me suggestions.

Thanks,

karthik.