data a;
   input stock $3. datetime price;
   informat datetime DATETIME16.;
   format datetime DATETIME16.;
cards;
NEC 17OCT91:14:45:32 3.00
NEC 17OCT91:14:45:35 4.00
NEC 17OCT91:14:45:33 4.00
NEC 17OCT91:14:45:32 3.50
NEC 17OCT91:14:45:35 3.50
;
proc sort data=a;by stock datetime;
proc print data=a(obs=20);
data b;set a;by stock datetime;if last.datetime;
proc print data=b(obs=20);
proc summary data=a;
   id stock;
   class datetime;
   var price;
   output out=c(drop=_type_ _freq_) mean=;
proc print data=c(obs=20);run;

谢谢 不过我是想取出每分钟内的最后一个数据  现在有思路了