Date:         Wed, 30 Nov 2005 10:39:55 -0600
Reply-To:     baogong jiang <bgjiang@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         baogong jiang <bgjiang@GMAIL.COM>
Subject:      help with LAG function
Content-Type: text/plain; charset=ISO-8859-1

hello, I have a dataset like following:

id  serv_from_date supply
a   20041001    30
a   20041102    30
a  20050204   15
b  20041125 30
b  20050212 45
b 20050301 30
c 20050312 30
d 20050612 15

 I want to calculate the gaps between the serv_from_date by each id;
data were sorted by id and serv_from_date


I used this:

data new;
set old;
by id:
if first.id then gap=.;
else gap=input(put (serv_from_date,8.),
yymmdd8.)-input(put(serv_from_date,8.),yymmdd8.);
run;

but code did not give me the right results.

what's wronge with the code?
anyone can give a sql solution?



thank you,