PL SQL Data Types Oracle PLSQL Tutorial

SQL> SET ECHO ON
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
  2    age   DATE;
  3    current_year NATURAL;
  4  BEGIN
  5    age := sysdate;
  6    current_year := TO_NUMBER(TO_CHAR(age,'yy'));
  7    DBMS_OUTPUT.PUT_LINE('current_year:');
  8    DBMS_OUTPUT.PUT_LINE(current_year);
  9  END;
 10  /
current_year:
7
PL/SQL procedure successfully completed.
SQL>