* Merging data sets;

data yr2001;
INPUT date $ 1-5 +1 temp weather $ ;
lines;
Jan 1 23 sun
Jan 2 34 sun
Jan 3 47 clouds 
Jan 5 32 snow
;
run;

data yr2002;
INPUT date $ 1-5 +1 temp weather $;
lines;
Jan 1 24 sleet
Jan 2 27 snow
Jan 3 28 snow
Jan 6 42 rain
Jan 8 32 clouds
;
run;

data yr2001; set yr2001;
temp2001=temp; weather2001=weather; 
drop temp weather;
data yr2002; set yr2002;
temp2002=temp; weather2002=weather; 
drop temp weather;
run;

/* Simple Merging */
data together;
merge yr2001 yr2002;
BY date;
run;

proc print data=together;
title 'Both 2001 and 2002 Weather';
run;