CREATE OR REPLACE TYPE userobj1 AS OBJECT
(
  col1 NUMBER(13),
  col2 NUMBER(13)
);

CREATE OR REPLACE TYPE userobj2 AS TABLE OF userobj1;

CREATE OR REPLACE TYPE num_array AS TABLE OF NUMBER(20);

DECLARE

       rec1 userobj1;

       rec2 userobj2 := userobj2();

       v_arr num_array;

       CURSOR cur IS
          SELECT LEVEL col1, LEVEL*10 col2 FROM dual CONNECT BY LEVEL < 10;  --there is no duplicate values here , this is for test only.

BEGIN

          OPEN cur;

          FETCH cur 
      	    BULK COLLECT 
		INTO rec1; --Error "ORA-06550: line 17, column 29: PLS-00497: cannot mix between single row and multi-row (BULK) in INTO LIST"

          SELECT col1 BULK COLLECT INTO v_arr FROM TABLE(CAST(rec1 AS userobj2 --or rec2 ?  have some doubts here please help on that too.
          ));

          FOR i IN 1 .. v_arr.COUNT 
              LOOP 
		dbms_output.put_line(v_arr(i)); 
	      END LOOP;

          CLOSE cur;

EXCEPTION 
          WHEN 
              OTHERS 
		 THEN 
		     IF cur%ISOPEN 
			  THEN 
			      CLOSE cur; 
		     END IF; 
											
			dbms_output.put_line(SQLERRM); 
											
			RAISE; 
END;

SELECT userobj1 (LEVEL, LEVEL*10) FROM dual CONNECT BY LEVEL < 10; 

CREATE OR REPLACE TYPE userobj1 AS OBJECT
(
  col1 NUMBER(13),
  col2 NUMBER(13)
);

CREATE OR REPLACE TYPE userobj2 AS TABLE OF userobj1;

CREATE OR REPLACE TYPE num_array AS TABLE OF NUMBER(20);


DECLARE

  rec2 userobj2 := userobj2();

  v_arr num_array;

  CURSOR cur IS
    SELECT userobj1(LEVEL, LEVEL) FROM dual CONNECT BY LEVEL < 10;

BEGIN

  OPEN cur;

  FETCH cur BULK COLLECT
    INTO rec2; 

  SELECT col2 BULK COLLECT INTO v_arr FROM TABLE(CAST(rec2 AS userobj2));

  FOR i IN 1 .. v_arr.COUNT
  LOOP
    dbms_output.put_line(v_arr(i));
  END LOOP;

  CLOSE cur;

EXCEPTION
  WHEN OTHERS THEN
    IF cur%ISOPEN
    THEN
      CLOSE cur;
    END IF;
  
    dbms_output.put_line(SQLERRM);
  
    RAISE;
END;

for i in 1..rec.col1.count
loop
dbms_output.put_line(rec.col1(i));

SQL> DECLARE
  2    rec2 userobj2 := userobj2();
  3    CURSOR cur IS
  4      SELECT userobj1(LEVEL, LEVEL) FROM dual CONNECT BY LEVEL < 10;
  5  BEGIN
  6    OPEN cur;
  7    FETCH cur BULK COLLECT INTO rec2;
  8    CLOSE cur;
  9    FOR i IN 1 .. rec2.COUNT
 10    LOOP
 11      dbms_output.put_line(rec2(i).col1||' '||rec2(i).col2);
 12    END LOOP;
 13  EXCEPTION
 14    WHEN OTHERS THEN
 15      IF cur%ISOPEN THEN CLOSE cur; END IF;
 16      RAISE;
 17  END;
 18  /
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