Date:         Mon, 11 May 2009 06:27:43 -0400
Reply-To:     Randy <randistan69@HOTMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Randy <randistan69@HOTMAIL.COM>
Subject:      Flagging multiple ID's on the same day

I want to flag multiple ID's (where ID_A and ID_B are one unit) that appear
in different "Code" on the same day:

My data set is as follows

Date     Code     ID_A     ID_B
May1      1        AB1      XZ
May1      1        AB1      MN
May1      2        AB1      XZ
May1      2        CD1      MN
May2      1        AB1      XZ
May2      1        CD1      MN
May2      2        CD1      MN
May2      2        AB1      MN

My output should be as follows:

Date     Code     ID_A     ID_B    Flag1
May1      1        AB1      XZ       1
May1      1        AB1      MN       0
May1      2        AB1      XZ       1
May1      2        CD1      MN       0
May2      1        AB1      XZ       0
May2      1        CD1      MN       1
May2      2        CD1      MN       1
May2      2        AB1      MN       0

The code that I wrote is as follows:
data need; set have;
by code ID_A ID_B date;
flag1 = 0;
if (first.ID_B and last.ID_B) then flag1 = 1;
run;

It does not work.  What mistake am I making?

Randy