How to write SQL statement when use Method in object relational database - oracle11g

Question

I am trying to create a small database of bank employees using method in oracle 11g, so at the end I can fetch values of those employees who are entitle for the awards at the end of the year:
Gold medals for employees who have been working at the bank for more than 12 years and supervised more than 6 staff; silver medals for employees who have been working at the bank for more than 8 years and supervised more than 3 staff; bronze medals for employees who have been working at the bank for
more than 4 years, displaying their names and Medal awarded (only
displaying those who have been awarded).
So here what I am doing
create type EmployeeName as object(
title varchar2(10),
firstName varchar2(20),
surname varchar2(20))
not final
/
create or replace type employeeaward as object(
empID integer,
eName EmployeeName,
number_staff_supervised int,
working_years int,
MEMBER FUNCTION award_given RETURN STRING,
MEMBER FUNCTION number_fraction (N real) RETURN real
);
/
CREATE OR REPLACE TYPE BODY employeeaward AS
MEMBER FUNCTION award_given RETURN STRING IS
BEGIN
IF self.working_years > 12 THEN
RETURN 'gold medal';
ELSIF self.working_years > 8 THEN
RETURN 'silver medal';
ELSIF self.working_years > 4 THEN
RETURN 'bronze medals';
END IF;
END award_given;
MEMBER FUNCTION number_fraction(N real) RETURN real IS
num real;
BEGIN
num :=(self.number_staff_supervised);
return num;
END number_fraction;
END;
and then create a table employeeawardtable of employeeaward like this:
create table employeeawardtable of employeeaward;
/
Then insert some values in the table
insert into employeeawardtable values('2001',EmployeeName('Mr','Rohit','Sharma'),'12','18');
/
insert into employeeawardtable values('2002',EmployeeName('Mr','Andrew','Darson'),'9','7');
/
insert into employeeawardtable values('2003',EmployeeName('Mrs','Sarah','Barlow'),'5','4');
/
insert into employeeawardtable values('2004',EmployeeName('Mr','Ram','Gopal'),'11','9');
/
**This is the SQL query, I am struggling to fetch data. **
select e.ename.firstname, e.award_given(),e.number_fraction(15)
from employeeawardtable e
where e.number_fraction() > 8;
Thanks.

Answer 1

Following are the issues with your code.
The number_fraction member function is invoked without a parameter in the predicate. This will throw an error, "ORA-06553: PLS-306: wrong number or types of arguments in call to 'NUMBER_FRACTION'"
Below is SQL for your requirement.
select e.ename.firstname, e.award_given()
from employeeawardtable e
where e.award_given() = 'gold medal' and e.number_staff_supervised > 6
or e.award_given() = 'silver medal' and e.number_staff_supervised > 3
or e.award_given() = 'bronze medal';
The member_function award_given is not returning a default value. This will throw an error. "ORA-06503: PL/SQL: Function returned without value". Fix the type body as below.
CREATE OR REPLACE TYPE BODY employeeaward AS
MEMBER FUNCTION award_given RETURN STRING IS
BEGIN
IF self.working_years > 12 THEN
RETURN 'gold medal';
ELSIF self.working_years > 8 THEN
RETURN 'silver medal';
ELSIF self.working_years > 4 THEN
RETURN 'bronze medals';
ELSE--newly added
RETURN 'no medal';--newly added
END IF;
END award_given;
MEMBER FUNCTION number_fraction(N real) RETURN real IS
num real;
BEGIN
num :=(self.number_staff_supervised);
return num;
END number_fraction;
END;
Now issue the SQL.
Output:
ENAME.FIRSTNAME E.AWARD_GIVEN()
Rohit gold medal
Ram silver medal