Function with for loop and parameter table/column names ... syntax help

Question

I'm trying to create a function that returns the distinct values and counts from a user defined schema/table/column.
The code below defines an object type [stats_on_column_obj] and creates a single table of this type [stats_on_column_tab].
The function is supposed to take three input variables: p_schema_name, p_table_name, p_column_name and return a table (above).
I can hard code a SELECT statement into the () ... but once I try to convert it to parameters & exec immediate I am stuck. The red section is where the issue is (i think).
Oracle 10g.
CREATE TYPE stats_on_column_obj IS OBJECT(
  COL_VAL      VARCHAR2(500),
  COL_VAL_CNT  NUMBER    (7)
CREATE TYPE stats_on_column_tab IS TABLE OF stats_on_column_obj;
CREATE OR REPLACE FUNCTION get_STATS_ON_COLUMN
   p_schema_name IN varchar2,
   p_table_name IN varchar2,
   p_column_name IN  varchar2
   RETURN STATS_ON_COLUMN_tab
IS
   l_STATS_ON_COLUMN_tab   STATS_ON_COLUMN_tab := STATS_ON_COLUMN_tab ();
   n                       INTEGER := 0;
   str_select_tbl          varchar2(5000);
BEGIN
   str_select_tbl := 'SELECT '||p_column_name||' as col_val, count(*) as col_val_cnt FROM '||p_schema_name||'.'||p_table_name||' group by '||p_column_name;
   FOR r IN (str_select_tbl)
   LOOP
      l_STATS_ON_COLUMN_tab.EXTEND;
      n := n + 1;
      l_STATS_ON_COLUMN_tab (n) := STATS_ON_COLUMN_obj (r.col_val, r.col_val_cnt);
   END LOOP ;
   RETURN l_STATS_ON_COLUMN_tab;
END;
[Error] PLS-00103 (124: 4): PLS-00103: Encountered the symbol "LOOP" when expecting one of the following:   * & - + / at mod remainder rem .. <an exponent (**)> ||   multiset year DAY_
[Error] PLS-00103 (126: 9): PLS-00103: Encountered the symbol "=" when expecting one of the following:   constant exception <an identifier>   <a double-quoted delimited-identifier> table LONG_ double ref   char time timestam
[Error] PLS-00103 (127: 29): PLS-00103: Encountered the symbol "(" when expecting one of the following:   constant exception <an identifier>   <a double-quoted delimited-identifier> table LONG_ double ref   char time timestam
[Error] PLS-00103 (128: 4): PLS-00103: Encountered the symbol "END" when expecting one of the following:   begin function package pragma procedure subtype type use   <an identifier> <a double-quoted delimited-identifier> form
SELECT * FROM TABLE (get_STATS_ON_COLUMN('SCHEMAS_X','TABLE_X','COLUMN_X'));

Answer 1

SCOTT@orcl > CREATE OR REPLACE
  2    FUNCTION get_STATS_ON_COLUMN(
  3                                 p_schema_name IN varchar2,
  4                                 p_table_name IN varchar2,
  5                                 p_column_name IN  varchar2
  6                                )
  7      RETURN STATS_ON_COLUMN_tab
  8      IS
  9          v_STATS_ON_COLUMN_tab STATS_ON_COLUMN_tab := STATS_ON_COLUMN_tab ();
10          v_n                   INTEGER := 0;
11          v_str_select_tbl      VARCHAR2(5000);
12      BEGIN
13          v_str_select_tbl := 'SELECT stats_on_column_obj(' || p_column_name || ',count(*)) FROM ' ||
14                              p_schema_name || '.' || p_table_name || ' group by ' || p_column_name;
15      EXECUTE IMMEDIATE v_str_select_tbl
16        BULK COLLECT
17        INTO v_STATS_ON_COLUMN_tab;
18       RETURN v_STATS_ON_COLUMN_tab;
19  END;
20  /
Function created.
SCOTT@orcl > select  *
  2            from  table(
  3                        get_STATS_ON_COLUMN(
  4                                            'SCOTT',
  5                                            'EMP',
  6                                            'JOB'
  7                                           )
  8                       )
  9  /
COL_VAL              COL_VAL_CNT
CLERK                          4
SALESMAN                       4
PRESIDENT                      1
MANAGER                        3
ANALYST                        2
SCOTT@orcl >
Or better change it to pipelined function.
SY.