I think you can use my code to solve it, see inside 回复：SAS编程：请赐

来源: 于 2008-04-27 20:52:44 [旧帖] [给我悄悄话] 本文已被阅读：次

Assuming 日期重叠次数 means the # of same startdate and enddate

proc freq data=datset1;
by ID;
Table startdate/out=outdatset2;
run;