merge If condition A then data set1 ,else data set 2

[Ronein]

Hello

What is the way to merge in the following way:

If condion A then merge from data set tbl1

If condion B then merge from data set tbl2

thanks

[PaigeMiller]

%macro conditional_merge;
data want;
     merge have
         %if &x=0 %then tbl1;
         %else %if &x>0 %then tbl2;
     ;
run;
%mend conditional_merge;
%conditional_merge