Question

Assume the following table:

TableA:

ID  GroupName SomeValue
1   C         1
2   C         1
2   B         1
2   A         1

I need to construct a query that selects the following result:

ID  GroupName SomeValue
1   C         1
1   B         0
1   A         0
2   C         1
2   B         1
2   A         1

The GroupName is actually derived from TableA column’s CASE expression and can take only 3 values: A, B, C.

Are the analytic functions the way to go?

EDIT

Sorry, for not mentioning it, but the ID could consist of multiple columns. Consider this example:

ID1 ID2 GroupName SomeValue
1   1   C         1

1   2   C         1

2   2   C         1
2   2   B         1
2   2   A         1

I need to pad SomeValue with 0 for each unique combination ID1+ID2. So the result should be like this:

ID1 ID2 GroupName SomeValue

1   1   C         1
1   1   B         0
1   1   A         0

1   2   C         1
1   2   B         0
1   2   A         0

2   2   C         1
2   2   B         1
2   2   A         1  

EDIT2
Seems like solution, proposed by @Laurence should work even for multiple-column ‘ID’. I couldn’t rewrite the query proposed by @Nicholas Krasnov to conform to this requirement. But could somebody compare these solutions performance-wise? Will the analytic function work faster than ‘cross join + left outer join’?

Answer 1

To fill in gaps, you could write a similar query using partition by clause of outer join:

SQL> with t1(ID,GroupName,SomeValue) as
  2  (
  3    select 1,   'C',   1  from dual union all
  4    select 2,   'C',   1  from dual union all
  5    select 2,   'B',   1  from dual union all
  6    select 2,   'A',   1  from dual
  7  ),
  8  groups(group_name) as(
  9    select 'A' from dual union all
 10    select 'B' from dual union all
 11    select 'C' from dual
 12  )
 13  select t1.ID
 14       , g.group_name
 15       , nvl(SomeValue, 0) SomeValue
 16    from t1
 17    partition by (t1.Id)
 18    right outer join groups g
 19       on (t1.GroupName = g.group_name)
 20    order by t1.ID asc, g.group_name desc
 21  ;

        ID GROUP_NAME  SOMEVALUE
---------- ---------- ----------
         1 C                   1
         1 B                   0
         1 A                   0
         2 C                   1
         2 B                   1
         2 A                   1

6 rows selected

UPDATE: Response to the comment.

Specify ID2 column in the partition by clause as well:

SQL> with t1(ID1, ID2, GroupName,SomeValue) as
  2  (
  3    select 1, 1, 'C', 1 from dual union all
  4    select 1, 2, 'C', 1 from dual union all
  5    select 2, 2, 'C', 1  from dual union all
  6    select 2, 2, 'B', 1  from dual union all
  7    select 2, 2, 'A', 1  from dual
  8  ),
  9  groups(group_name) as(
 10    select 'A' from dual union all
 11    select 'B' from dual union all
 12    select 'C' from dual
 13  )
 14  select t1.ID1
 15       , t1.ID2
 16       , g.group_name
 17       , nvl(SomeValue, 0) SomeValue
 18    from t1
 19    partition by (t1.Id1, t1.Id2)
 20    right outer join groups g
 21    on (t1.GroupName = g.group_name)
 22  order by t1.ID1, t1.ID2  asc , g.group_name desc
 23  ;

       ID1        ID2 GROUP_NAME  SOMEVALUE
---------- ---------- ---------- ----------
         1          1 C                   1
         1          1 B                   0
         1          1 A                   0
         1          2 C                   1
         1          2 B                   0
         1          2 A                   0
         2          2 C                   1
         2          2 B                   1
         2          2 A                   1

9 rows selected