Hi ,
Where you have written your code for SAVE command there only you will have to write for GET command.
Your code should look something like this:
CASE SY-UCOMM " You can use your own variable also here.
WHEN 'SAVE'.
perform f_save_data.
WHEN 'GET'.
perform f_get_data.
form f_get_data.
*** Select the data here from the database.
endform.
Hope this helps.