PL/SQL: procedure to process a comparison between two tables

This is an example what i need :

Table 1 :

Id  champ1 champ2 champ3
   1      A      S      Q
   2      D      K      A
   3      D      A      S

Table 2:

Id  champ1 champ2 champ3
   1      A      S      Q
   2      Q      A      A
   3      A      A      K  

A procedure that feeds a table3 as a result of comparison between the table 1 and table 2

Table 3:

Id_exc name_champ noted_val except_val
   2    champ1       D         Q
   3    champ1       D         A
   2    champ2       K         A
   3    champ3       S         K

Please, i need help if someone had the same challenge :)

Thanks in advanced

via Chebli Mohamed