各位好：
   请问sas中有什么命令能统计数据库中记录条目数。
  我想在数据库中记录数为0的时候，终止循环程序。

%macro BA(district);
**;
%let i=1;
%let j=1;
%let k=0;

data case1;
set &district;
if cancer=1;
group="case";

data control1;
set &district;
if cancer=2;
group="control";
proc sort data=case1;
by a_age x;
proc sort data=control1;
by a_age x;


%do %while (&k>=0);
proc surveyselect data=case&i out=case_&j seed=25892587 method=srs n=1;
strata a_age;
run;

data case_middle;
  set case&i case_&j;
run;
proc sort data=case_middle;
by x;
%let i=%eval(&i+1);
data case&i;
    set case_middle;
    by x;
    if first.x and last.x;
    %if _n_=0  %then %goto exit;*******问题就在这里

run;
%let j=%eval(&j+1);

%end;
%mend ba;
%ba(shandong)