how to write loop for a record type in oracle

I have the following statement which compiles fine in my package:

package header:

   TYPE role_user_type IS RECORD (
      ROLE_ID        some_table.RO开发者_开发技巧LE_ID%TYPE,
      SUBGROUP       some_table.USER_ID%TYPE
   );

body:

ROLE_USER_REC                  MY_PACKAGE.ROLE_USER_TYPE;

SELECT B.USER_ID, B.ROLE INTO ROLE_USER_REC
FROM some_table where user_id like 'M%'

what is the skeleton for looping through ROLE_USER_REC? can we even loop through it?

There is nothing to loop.

role_user_type defines a single record, that you can access via:

dbms_output.put_line( role_user_rec.role_id || ', ' || role_user_rec.subgroup );

Your SELECT ... INTO will fail as soon as more than one row is returned.

If you need to store several of those records, you can use nested tables like
TYPE role_user_tab IS TABLE OF role_user_type:

Example:

DECLARE
  TYPE role_user_type IS RECORD (
     ROLE_ID        VARCHAR2(10),
     SUBGROUP       VARCHAR2(10)
  );
  TYPE role_user_tab IS TABLE OF role_user_type;
  role_user_rec role_user_tab;
BEGIN
  SELECT 'A', 'B'
  BULK COLLECT INTO role_user_rec
  FROM dual;
  FOR i IN role_user_rec.FIRST .. role_user_rec.LAST LOOP
    dbms_output.put_line( role_user_rec(i).role_id || ', ' || role_user_rec(i).subgroup );
  END LOOP;
END;

You can use a cursor FOR loop:

BEGIN
  FOR role_user_type IN ('SELECT B.USER_ID, B.ROLE FROM some_table where user_id like ''M%'')
  LOOP
    dbms_output.put_line('User ID: '||role_user_type.user_id);
    etc...
  END LOOP;
END;

Another alternative:

DECLARE
  CURSOR C IS
SELECT B.USER_ID, B.ROLE 
  FROM some_table 
 where user_id like 'M%';
BEGIN
  FOR role_user_type IN C LOOP
    dbms_output.put_line('User ID: '||role_user_type.user_id);
    etc...
  END LOOP;
END;

You can use cursors for this

FOR i in (/* Your Select query*/)
loop
/* You can use value of the column fetched from select query like i.column_name
and use it which ever way you want */
end loop;