drop type column_names
/

drop type tab_column_object
/

CREATE TYPE tab_column_object AS OBJECT
(
 column_name VARCHAR2( 30 )
 )
/

CREATE TYPE column_names AS TABLE OF tab_column_object
/

create or replace function use_plsql_tab(p_table IN all_tab_columns.table_name%TYPE) 
return column_names
is
v_tab_cols_name column_names:=column_names();
cursor c_tables(p_table all_tab_columns.table_name%TYPE) is
 select column_name from all_tab_columns where upper(table_name)=upper(p_table);
v_cnt NUMBER( 16 ) default  0 ;
begin
 for v_cur in c_tables(p_table) loop
    v_tab_cols_name.extend;
  v_tab_cols_name(v_tab_cols_name.count):=v_cur;
 end loop;
 return v_tab_cols_name;
end use_plsql_tab;
/

select * from table(cast(use_plsql_tab('all_tab_columns') as column_names));

test@RU_MOW_EPSILON.WORLD> start use_plsql_tab

Type dropped.


Type dropped.


Type created.


Type created.


Function created.

NUM_BUCKETS
LAST_ANALYZED
SAMPLE_SIZE
CHARACTER_SET_NAME
CHAR_COL_DECL_LENGTH
GLOBAL_STATS
USER_STATS
AVG_COL_LEN
OWNER
TABLE_NAME
COLUMN_NAME
DATA_TYPE
DATA_TYPE_MOD
DATA_TYPE_OWNER
DATA_LENGTH
DATA_PRECISION
DATA_SCALE
NULLABLE
COLUMN_ID
DEFAULT_LENGTH
DATA_DEFAULT
NUM_DISTINCT
LOW_VALUE
HIGH_VALUE
DENSITY
NUM_NULLS

 26  rows selected.

test@RU_MOW_EPSILON.WORLD>