Help with this sql. Select only employees from a distinct Org??

Question

Hi guys, simple query.
create table balancetest(emp_id number, balance_id number, balance number, org number);
insert into balancetest values (111, 1, 1, 0);
insert into balancetest values (111, 1, 1, 0);
insert into balancetest values (111, 2, 1, 1);
insert into balancetest values (222, 1, 2, 1);
insert into balancetest values (333, 3, 4, 3);
insert into balancetest values (333, 3, 4, 2);
commit;
SQL> select * from balancetest;
    EMP_ID BALANCE_ID    BALANCE        ORG
       111          1          1          0
       111          1          1          0
       111          2          1          1
       222          1          2          1
       333          3          4          3
       333          3          4          2
6 rows selected.As you can see, emp_id 111 appears on different Org (0 and 1). I need to calculate the balance but the requirement says that I need to retrieve employees appearing only in 1 org.. It won't matter which org is selected (the business rules ensure balance will be the same), as long as if an employee is in multiple org, this employee is selected only once for an org. So, my result will be something like:
    EMP_ID BALANCE_ID    BALANCE        ORG
       111          1          1          0
       111          1          1          0
       222          1          2          1
       333          3          4          3
       333          3          4          2or,
    EMP_ID BALANCE_ID    BALANCE        ORG
       111          2          1          1
       222          1          2          1
       333          3          4          3
       333          3          4          2In other words, an employee must appear only in 1 org in my result.
any ideas? I tried:
select * from balancetest bal1
where not exists ( select bal2.emp_id from
                           balancetest bal2
                           where bal2.emp_id = bal1.emp_id
                           and bal2.org <> bal1.org
                           );But I guess it won't be that simple!!

Answer 1

Hi,
You can find the lowest-numbered org for each employee like this:
SELECT    emp_id
,         MIN (org)  AS min_org
FROM      balancetest
GROUP BY  emp_id;You can get the results you want by selecting only rows from balancetest that match a row in this the result set above. There are many ways to do that, such as a join:
WITH  g  AS
    SELECT    emp_id
    ,         MIN (org)  AS min_org
    FROM      balancetest
    GROUP BY  emp_id
SELECT  b.*
FROM    balancetest  b
JOIN                 g  ON  b.emp_id = g.emp_id
                        AND b.org    = g.min_org;