Why Left Outer Join Doesn't Work?

Question

Hello
I have a query that I want to return all group id's in the grp_id table and count and give me a count of all members that are "active" in the member table. There are some members that are not active in the member table that belong to groups in the grp_id table. I still want a record returned for those grpid's, though since there are no active members for those groups, I would want a zero as the mbr_count. An active mbr is one whose eff_dt is less than today's date and whose exp_dt is greater than todays date.
I have listed the query below, which returns active mbr records, but unfortuntely, does not return the one grpid (as in my sample data) that does not have an active member (grpid: 'D'). I have also provided the DDL for the two tables along with some sample data that gives me the (Incorrect) results I have posted. I have also posted what results I need (the 'Correct' results).
Thanks for any assistance.. (I am using PL/SQL)
QUERY I AM USING:
=============
SELECT
g00.grpid,
count(m00.grpid) mbr_count
FROM
grp_id g00
LEFT OUTER JOIN
mbr m00 on
g00.grpid = m00.grpid
WHERE
m00.eff_dt < sysdate
AND
m00.exp_dt > sysdate
GROUP BY
g00.grpid
it gives me results as:
INCORRECT RESULTS:
===============
GRPID     MBR_COUNT
A     2
B     2
C     1
What I want to see is:
CORRECT RESULTS
===============
GRPID     MBR_COUNT
A     2
B     2
C     1
D     0
Here is the DDL's and Sample Data:
create table grp_id (grpid varchar(1))
insert into grp_id values ('A')
insert into grp_id values ('B')
insert into grp_id values ('C')
insert into grp_id values ('D')
commit
create table mbr (mbr_name varchar(10), grpid varchar(1), eff_dt date, exp_dt date)
insert into mbr values ('MARK', 'A', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'))
insert into mbr values ('MARK', 'A', to_date('07-01-2011', 'MM-DD-YYYY'), to_date('01-01-2012', 'MM-DD-YYYY'))
insert into mbr values ('MARTY', 'A', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'))
insert into mbr values ('MARTY', 'A', to_date('07-01-2011', 'MM-DD-YYYY'), to_date('01-01-2012', 'MM-DD-YYYY'))
insert into mbr values ('FRANK', 'B', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'))
insert into mbr values ('FRANK', 'B', to_date('07-01-2011', 'MM-DD-YYYY'), to_date('01-01-2012', 'MM-DD-YYYY'))
insert into mbr values ('MARY', 'B', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'))
insert into mbr values ('MARY', 'B', to_date('07-01-2011', 'MM-DD-YYYY'), to_date('01-01-2012', 'MM-DD-YYYY'))
insert into mbr values ('JEAN', 'C', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'))
insert into mbr values ('JEAN', 'C', to_date('07-01-2011', 'MM-DD-YYYY'), to_date('01-01-2012', 'MM-DD-YYYY'))
insert into mbr values ('NOAM', 'D', to_date('01-01-2011', 'MM-DD-YYYY'), to_date('07-01-2011', 'MM-DD-YYYY'))

Answer 1

Thanks for the script, shame about the missing semi-colons :)
Your restrictions on date are implemented as "filter predicates" rather than "join predicates".
i.e. the difference between a WHERE instead of extra ANDs in the JOIN clause.
SQL> SELECT
  2  g00.grpid,
  3  count(m00.grpid) mbr_count
  4  FROM
  5  grp_id g00
  6  LEFT OUTER JOIN
  7  mbr m00 on
  8  g00.grpid = m00.grpid
  9  WHERE
10  m00.eff_dt < sysdate
11  AND
12  m00.exp_dt > sysdate
13  GROUP BY
14  g00.grpid
15  /
G  MBR_COUNT
A          4
B          4
C          2
SQL> SELECT
  2  g00.grpid,
  3  count(m00.grpid) mbr_count
  4  FROM
  5  grp_id g00
  6  LEFT OUTER JOIN
  7  mbr m00 on
  8  g00.grpid = m00.grpid
  9  AND
10  m00.eff_dt < sysdate
11  AND
12  m00.exp_dt > sysdate
13  GROUP BY
14  g00.grpid;
G  MBR_COUNT
D          0
A          4
B          4
C          2
SQL>