we can use the set and merge commands to join the datas,use
merge if u like to joining data tables that has similar
observation  and diff observation and relatted variable mean
use SET ,V can also use proc sql joing the data tables ,i am
beginner on sas so if any one have differ with my ans just
post to my mail kumarravi111@gmail.com

Use proc sql for joins,

There are 5 types of joins in sas

1) Inner Join :- Output would be only matched cases.

2) left outer Join :- Output would be all the rows from 
left table with corresponding matched value from right 
table.

3) right Join :- vice versa of left Join.

4) Full outer join :- will take all matched & unmatched 
rows of both the tables.

5) Product Join :- this will join the 2 tables without any 
common variable.