OPTIONS LS=64 NONUMBER NODATE NOCENTER;

***************************************;
*** Combining data sets by stacking ***;
***************************************;

DATA in1; INPUT year x @@; CARDS;
     1996 12   1996 15
;
PROC PRINT DATA=in1;

DATA in2; INPUT year x y @@; CARDS;
     1997 13 20  1997 10 27
;
PROC PRINT DATA=in2;

/* Stack in1 and in2 to form both */

DATA both; SET in1 in2;

PROC PRINT DATA=both;
     VAR x y year;
RUN;

***************************************;
*** Combining data sets by merging ***;
***************************************;

DATA m1; INPUT year x1 x2 @@; CARDS;
     1996 2 3   1997 1 4
;
PROC PRINT DATA=m1;

DATA m2; INPUT year y1 y2 @@; CARDS;
     1997 100 120   1996 110 130
;
PROC PRINT DATA=m2;

/* data sets must be sorted by merging
   variable(s) before merging */

PROC SORT DATA=m1; BY year;
PROC SORT DATA=m2; BY year;

DATA both;   MERGE m1 m2; 
     BY year;

PROC PRINT DATA=both;
     ID year;
     VAR x1 y1 x2 y2;
RUN;