SQL Question

From: Gigi Lipori <pflugg_at_bellsouth.net>
Date: Fri, 20 Sep 2002 09:05:51 -0400
Message-ID: <3d8b1c20$1_3_at_corp-news.newsgroups.com>

I have query a, which works great with one exception. It outputs results b.What I'm trying to do is print the encounter of interest, and note the previous encounter next to it. I want to get a record that would show his 6/13 encounter with a blank for his previous encounter. I thought by doing an outer join to the Encounters alias I could accomplish that, but it doesn't work. Anyway, I think I'm being obtuse, but I can't get it. Any thoughts would be appreciated.

QUERYA SELECT
  ENCOUNTERS.START_DATE,
  max(ENCOUNTERS2.START_DATE)
FROM
  ENCOUNTERS,
  ENCOUNTERS ENCOUNTERS2,
  EXT_PAT_IDS,
  PATIENT_DEMO
WHERE
  ( PATIENT_DEMO.PAT_ID=EXT_PAT_IDS.PAT_ID )

  AND  ( EXT_PAT_IDS.EXT_PAT_ID_TYPE = 2  )
  AND  ( ENCOUNTERS.PAT_ID(+)=PATIENT_DEMO.PAT_ID  )
  AND  ( PATIENT_DEMO.PAT_ID=ENCOUNTERS2.PAT_ID(+)  )
  AND  ( ENCOUNTERS2.START_DATE  <  ( ENCOUNTERS.START_DATE )  )
  AND  (

  EXT_PAT_IDS.EXT_PAT_ID = '01216116'
  )
GROUP BY
  ENCOUNTERS.START_DATE RESULTS B Encounter Date, Previous Encounter Date

7/31/2000, 6/13/2000
8/7/2000, 7/31/2000
8/14/2000, 8/7/2000
8/21/2000, 8/14/2000
9/5/2000, 8/21/2000
10/2/2000, 9/5/2000
1/24/2001, 10/2/2000

3/26/2001, 1/24/2001
4/23/2001, 3/26/2001

LOOKING FOR AN ADDITIONAL RECORD THAT WOULD BE 6/13/2000, [NULL] Received on Fri Sep 20 2002 - 15:05:51 CEST