Convert row to column and delete id which repeating.

Question

In target table i should load winner_id first and then respective looser_id's of all winner_id.
input
table name:merger
sno winner_id looser_id
1 100 200
2 304 500
3 100 400
4 456 700
5 100 987
my output should be as below
100
200
400
987
304
456

Answer 1

979693 wrote:
if i use union i will not get ids in sequence.So you want all distinct winners first followed by all distinct loosers. I'll assume if same id is both winner & looser it will appear once as a winner. If so, use:
with  t as (
             select  winner_id id,
                     1 weight
               from  merger
            union all
             select  looser_id,
                     2 weight
               from  merger
select  id
  from  t
  group by id
  order by min(weight),
           id
/For example:
SQL> with merger as (
  2                  select 1 sno,100 winner_id,200 looser_id from dual union all
  3                  select 2,304,500 from dual union all
  4                  select 3,100,400 from dual union all
  5                  select 4,456,700 from dual union all
  6                  select 5,100,987 from dual
  7                 ),
  8            t as (
  9                   select  winner_id id,
10                           1 weight
11                     from  merger
12                  union all
13                   select  looser_id,
14                           2 weight
15                     from  merger
16                 )
17  select  id
18    from  t
19    group by id
20    order by min(weight),
21             id
22  /
        ID
       100
       304
       456
       200
       400
       500
       700
       987
8 rows selected.
SQL>  SY.