How to translate.....

Hi,

I want to translate lab's drug code in lab data into its full name based on
following med data info.

varibales:
ondrug: indicator for drug on use.
sub: non-protocol visit
repdt: lab result report date
visdt: visit date
..........

in final dataset, in sub-visit 0 code d should be translated into dnam1
in sub-visit 3 code d should be traslated into dnam2


Thanks.


************************************************** ***********;
data med;
input visn sub visdt: date7. drgnam$ ondrug;
datalines;
1 0 12apr03 lnam1 1
1 0 12apr03 dnam1 1
1 2 14apr03 lnam1 1
1 2 14apr03 dnam1 0
1 2 14apr03 dnam2 1
2 1 05may03 lnam1 1
2 1 05may03 dnam2 1
........
;
run;

data lab;
input visn sub repdt: date7. drgcode $ ;
datalines;
1 0 13apr03 l
1 0 13apr03 d
1 3 04may03 l
1 3 04may03 d
...........
;
run;
************************************************** ***********;