Is there a difference between LEFT Outer JOIN and RIGHT Outer JOIN?

[cosmid]

Thanks

[Patrick]

Keep all rows from the left side as opposed to keep all rows from the right side. But if you have a left join formulated and then switch to a right join and also switch your source tables accordingly then the result will be the same.

[cosmid]

So they are essentially the same?

[Patrick · Accepted solution]

Depending on how you look at it - yes.

data have1;
  var1=1;
  do id=1,3,6;
    output;
  end;
run;
data have2;
  var2=1;
  do id=1 to 5;
    output;
  end;
run;

proc sql;
  select t1.id, t1.var1, t2.var2
  from have1 t1 left join have2 t2
    on t1.id=t2.id
  ;
quit;

proc sql;
  select t1.id, t1.var1, t2.var2
  from have2 t2 right join have1 t1
    on t1.id=t2.id
  ;
quit;