using macro to merge unknown number of sas data sets by a common variable

For example, you have many data sets as DATA1, DATA2, DATA3, ... , DATAn, and n is unknown. All these data sets have one common variable COMMON. Now you need to merge these data sets by COMMON.

data data1;

  input common a1;

  cards;

  2 3

  3 4

  4 5

  ;

  run;

data data2;

  input common a2;

  cards;

  21 3

  31 4

  41 5

  ;

  run;

%macro combineall (n);

  data combine;

   merge

   %do i=1 %to &n;

     DATA&i

   %end;  /* This ; is for end */

   ;      /* This ; is for merge */

         by COMMON;

%mend;

%allcombine(2)

proc print data=combine;

run;