Looks like you have it figured out yourself by using a classic data step way. Although I think it is worth mentioning that for this kind of task, SQL seems to have a native edge, as SQL join generates Cartesian products to start with. proc sql; create table c as select * from a,b; quit; BTW, with the advent of Hash(), data step has been granted the similar power as SQL join: data c (drop=_:);   if _n_=1 then do;   set a (obs=1); dcl hash h(dataset:'a', ordered:'a'); h.definekey(all:'y'); h.definedone(); dcl hiter hi('h');   end;   set b;   _rc=hi.first();   do while (_rc=0); output; _rc=hi.next(); end; run; Kindly regards, Haikuo ... View more