Problem with Grouping Query

Question

I am having trouble with a query.
Table 1
id     status
1      STARTED
2      STARTED
3      STARTED
4      STARTED
5      STARTED
6      INCOMPLETE
7      INPROGRESS
Table 2
id     individual
1      MMJ
1      JBJ
2      MKJ
3     MKJ
3      LJJ
4      MMJ
5      MMJ
5      JBJ
6      ADJ
7      ADJ
The two tables are linked by id.
The user wants to see the count of STARTED projects for two groups.
Group 1 is MMJ, JBJ, ADJ
Group 2 is MKJ, LJJ
These groups aren’t assigned anywhere in the schema – I just got a list of names and what group they should go into…
How do I go about grouping the individuals and then how do I perform the count?
I did do a count and group by individual but my results are skewed because I get a double count on the ids that have multiple individuals assigned. Can anyone provide some insight?
Thank You!

Answer 1

SELECT
   SUM(group1),
   SUM(group2)
FROM
    SELECT DISTINCT
       t1.id,
       DECODE(t2.individual, 'MMJ', 1, 'JBJ', 1, 'ADJ', 1, 0) group1,
       DECODE(t2.individual, 'MKJ', 1, 'LJJ', 1, 0) group2
    FROM
       (select 1 id, 'STARTED' status from DUAL
        union
        select 2 id, 'STARTED' status from DUAL
        union
        select 3 id, 'STARTED' status from DUAL
        union
        select 4 id, 'STARTED' status from DUAL
        union
        select 5 id, 'STARTED' status from DUAL
        union
        select 6 id, 'INCOMPLETE' status from DUAL
        union
        select 7 id, 'INPROGRESS' status from DUAL
       ) t1,
       (select 1 id, 'MMJ' individual from dual
        union
        select 1 id, 'JBJ' individual from dual
        union
        select 2 id, 'MKJ' individual from dual
        union
        select 3 id, 'MKJ' individual from dual
        union
        select 3 id, 'LJJ' individual from dual
        union
        select 4 id, 'MMJ' individual from dual
        union
        select 5 id, 'MMJ' individual from dual
        union
        select 5 id, 'JBJ' individual from dual
        union
        select 6 id, 'ADJ' individual from dual
        union
        select 7 id, 'ADJ' individual from dual
       ) t2
    WHERE
       t1.id = t2.id AND
       t1.status = 'STARTED'
SUM(GROUP1) SUM(GROUP2)
          3           2