Using distinct on several columns

Question

Dear all;
I am have a query of the following form
select distinct id, zoneid, close_date from table_one
which gave a different result
from the same query with a different form
select distinct close_date, id, zoneid from table_one
Hence, I would like to understand why and how the phrase distinct is being used when utilizied in several columns.
THank you

Answer 1

By all means, feel free to post a testcase that we can reproduce, along with your database version ( the result of: select * from v$version; ).
My gut feeling is that this has to do with your unknown data and unknown datatypes...or 'very maybe' your database version.
SQL> create table table_one as
  2  select 1 id, 1 zoneid, to_date('01-01-2010 22:22:22', 'dd-mm-yyyy hh24:mi:ss') close_date from
dual union
  3  select 1, 1 zoneid, to_date('01-01-2010 22:22:22', 'dd-mm-yyyy hh24:mi:ss') from dual union
  4  select 1, 1 zoneid, to_date('01-01-2010 22:22:23', 'dd-mm-yyyy hh24:mi:ss') from dual;
Table created.
SQL> select distinct id, zoneid, close_date from table_one;
        ID     ZONEID CLOSE_DATE
         1          1 01-01-2010 22:22:23
         1          1 01-01-2010 22:22:22
2 rows selected.
SQL> select distinct close_date, id, zoneid from table_one;
CLOSE_DATE                  ID     ZONEID
01-01-2010 22:22:23          1          1
01-01-2010 22:22:22          1          1
2 rows selected.Both outcomes are just as expected...