一.运用By语句
proc sort data=data-set1 out=data-set2；
by var1;
run;
proc sort data=data-set3 out=data-set4;
by var1;
run;
data data-set5;
merge data-set2 data-set3;
by var1;
run;
（二）SQL（join,left join,right join,full join） [join相当于交集；merge相当于full join,并集]
proc sql;
select * from dataset1 left join dataset2
on dataset1.id=dataset2.id;
quit;