观测子集的形成

/* 同时定义3个数据集A,B,C */
DATA A B C;
	SET SASHELP.CLASS;
	IF age='11' THEN OUTPUT A;
	ELSE IF age='12' THEN OUTPUT B;
	ELSE OUTPUT C;
RUN;

PROC PRINT DATA=A;
RUN;

PROC PRINT DATA=B;
RUN;

PROC PRINT DATA=C;
RUN;