How Oracle's stored procedures return result sets

Procedure returns the recordset:
CREATE OR REPLACE PACKAGE pkg_test
As
TYPE Myrctype is REF CURSOR;

PROCEDURE Get (p_id number, p_rc out myrctype);
End Pkg_test;
/

CREATE OR REPLACE PACKAGE body pkg_test
As
PROCEDURE Get (p_id number, p_rc out Myrctype)
Is
Sqlstr VARCHAR2 (500);
BEGIN
IF p_id = 0 THEN
OPEN P_RC for
SELECT ID, NAME, sex, address, postcode, birthday
from student;
ELSE
SQLSTR: =
' Select Id,name,sex,address,postcode,birthday
From student where id=:w_id ';
OPEN P_RC for sqlstr USING p_id;
End IF;
End get;
End Pkg_test;
/

function returns the recordset:
Create packages and packages and functions with REF CURSOR definitions:
CREATE OR REPLACE
Package Pkg_test AS
/* Define REF CURSOR type
No return type, for weak type, allow dynamic SQL query,
Otherwise, it is strongly typed and cannot use dynamic SQL queries;
*/
Type myrctype is REF CURSOR;

--Function declaration
function get (IntID number) return myrctype;
End Pkg_test;
/

CREATE OR REPLACE
Package Body Pkg_test AS
--Function body
function get (IntID number) return Myrctype is
RC Myrctype; --Define REF CURSOR variable
Sqlstr VARCHAR2 (500);
Begin
If Intid=0 Then
--static testing, directly returning results directly with SELECT statement
Open RC for select id,name,sex,address,postcode,birthday from student;
Else
--Dynamic SQL assignment, using: w_id to declare that the variable is obtained externally
SQLSTR: = ' Select Id,name,sex,address,postcode,birthday from student where id=:w_id ';
--Dynamic test, return the result with SQLSTR string, pass parameter with using keyword
Open RC for sqlstr using IntID;
End If;

return RC;
End get;

End Pkg_test;