Help needed with nested tables

Question

I have two identical relations R and S defined as:
CREATE TYPE table_typ AS TABLE OF VARCHAR2(8);
CREATE TABLE R(
a INTEGER,
b table_type)
NESTED TABLE b STORE as b_1;
CREATE TABLE S(
a INTEGER,
b table_type)
NESTED TABLE b STORE as b_2;
Both have two tuples each:
INSERT INTO r VALUES (1, table_type('a','b'));
INSERT INTO r VALUES (2, table_type('d'));
INSERT INTO s VALUES (1, table_type('b','c'));
INSERT INTO s VALUES (3, table_type('e'));
Would it be possible to write a query that "unions" R and S so that nested tables in tuples (in R and S) that agree on the A attribute are merged together, while tuples that do not agree on A still appear in the result? That is, the result I am looking for is:
A B
1 TABLE_TYPE('a','b','c')
2 TABLE_TYPE('d')
3 TABLE_TYPE('e')
I've tried a simple union, but it does not work. Any help on this would be greatly appreciated.
Thanks,
Laura

Answer 1

I don't have 10g, but the following is a 9i solution. I know there has to be a better way. About all I can say for the code below is that it works. I am only posting it because it is better than nothing, until somebody with 10g posts something better. I have included the stragg function by Tom Kyte.
scott@ORA92> -- test data:
scott@ORA92> CREATE OR REPLACE TYPE table_type AS TABLE OF VARCHAR2 (8);
  2  /
Type created.
scott@ORA92> CREATE TABLE r(
  2    a INTEGER,
  3    b table_type)
  4    NESTED TABLE b STORE as b_1
  5  /
Table created.
scott@ORA92> CREATE TABLE s(
  2    a INTEGER,
  3    b table_type)
  4    NESTED TABLE b STORE as b_2
  5  /
Table created.
scott@ORA92> INSERT INTO r VALUES (1, table_type('a','b'));
1 row created.
scott@ORA92> INSERT INTO r VALUES (2, table_type('d'));
1 row created.
scott@ORA92> INSERT INTO s VALUES (1, table_type('b','c'));
1 row created.
scott@ORA92> INSERT INTO s VALUES (3, table_type('e'));
1 row created.
scott@ORA92> commit
  2  /
Commit complete.
scott@ORA92> -- start of code from Tom Kyte:
scott@ORA92> create or replace type string_agg_type as object
  2  (
  3       total varchar2(4000),
  4 
  5       static function
  6            ODCIAggregateInitialize(sctx IN OUT string_agg_type )
  7            return number,
  8 
  9       member function
10            ODCIAggregateIterate(self IN OUT string_agg_type ,
11                        value IN varchar2 )
12            return number,
13 
14       member function
15            ODCIAggregateTerminate(self IN string_agg_type,
16                          returnValue OUT  varchar2,
17                          flags IN number)
18            return number,
19 
20       member function
21            ODCIAggregateMerge(self IN OUT string_agg_type,
22                      ctx2 IN string_agg_type)
23            return number
24  );
25  /
Type created.
scott@ORA92> create or replace type body string_agg_type
  2  is
  3 
  4  static function ODCIAggregateInitialize(sctx IN OUT string_agg_type)
  5  return number
  6  is
  7  begin
  8        sctx := string_agg_type( null );
  9        return ODCIConst.Success;
10  end;
11 
12  member function ODCIAggregateIterate(self IN OUT string_agg_type,
13                             value IN varchar2 )
14  return number
15  is
16  begin
17        self.total := self.total
18        || ','
19        || value;
20        return ODCIConst.Success;
21  end;
22 
23  member function ODCIAggregateTerminate(self IN string_agg_type,
24                               returnValue OUT varchar2,
25                               flags IN number)
26  return number
27  is
28  begin
29        returnValue := ltrim(self.total,',');
30        return ODCIConst.Success;
31  end;
32 
33  member function ODCIAggregateMerge(self IN OUT string_agg_type,
34                           ctx2 IN string_agg_type)
35  return number
36  is
37  begin
38        self.total := self.total || ctx2.total;
39        return ODCIConst.Success;
40  end;
41 
42 
43  end;
44  /
Type body created.
scott@ORA92> CREATE or replace
  2  FUNCTION stragg(input varchar2 )
  3  RETURN varchar2
  4  PARALLEL_ENABLE AGGREGATE USING string_agg_type;
  5  /
Function created.
scott@ORA92> -- end of code from Tom Kyte
scott@ORA92> -- usage of above function:
scott@ORA92> COLUMN c FORMAT A15
scott@ORA92> SELECT a, stragg (column_value) AS c
  2  FROM   (SELECT t1.a, t1.column_value
  3            FROM   (SELECT r.a, c.column_value
  4                 FROM   r, TABLE (r.b) c) t1,
  5                (SELECT s.a, d.column_value
  6                 FROM   s, TABLE (s.b) d) t2
  7            WHERE  t1.a = t2.a
  8            UNION
  9            SELECT t1.a, t2.column_value
10            FROM   (SELECT r.a, c.column_value
11                 FROM   r, TABLE (r.b) c) t1,
12                (SELECT s.a, d.column_value
13                 FROM   s, TABLE (s.b) d) t2
14            WHERE  t1.a = t2.a)
15  GROUP  BY a
16  UNION ALL
17  SELECT a, stragg (column_value) AS c
18  FROM   (SELECT t1.a, t1.column_value
19            FROM   (SELECT r.a, c.column_value
20                 FROM   r, TABLE (r.b) c) t1,
21                (SELECT s.a, d.column_value
22                 FROM   s, TABLE (s.b) d) t2
23            WHERE  t1.a = t2.a (+)
24            AND    t2.a IS NULL
25            UNION
26            SELECT t2.a, t2.column_value
27            FROM   (SELECT r.a, c.column_value
28                 FROM   r, TABLE (r.b) c) t1,
29                (SELECT s.a, d.column_value
30                 FROM   s, TABLE (s.b) d) t2
31            WHERE  t1.a (+) = t2.a
32            AND    t1.a IS NULL)
33  GROUP  BY a
34  /
         A C
         1 a,b,c
         2 d
         3 e