Name: Calc_Anniversary

Input: Pay_Date, Hire_Date, Termination_Date

Output: "Y" if is the anniversary of the employee's Hire_Date, "N" if it is not, and "T" if he has been terminated before his anniversary.

Description: Create local variables to hold the month and day of the employee's Date_of_Hire, Termination_Date, and of the processing date using the TO_CHAR function. First check to see if he was terminated before his anniversary. The anniversary could be on any day during the pay period, so there will be a loop to check all 14 days in the pay period to see if one was his anniversary.

  CREATE OR replace FUNCTION Calc_anniversary(
   incoming_anniversary_date IN VARCHAR2)
   RETURN BOOLEAN
   IS
 hiredate        VARCHAR2(20);
 terminationdate VARCHAR(20);
 employeeid      VARCHAR2(38);
 paydate         NUMBER := 0;
 BEGIN
SELECT Count(arndt_raw_time_sheet_data.pay_date)
INTO   paydate
FROM   arndt_raw_time_sheet_data
WHERE paydate = incoming_anniversary_date;

WHILE paydate <= 14 LOOP
    SELECT To_char(employee_id, '999'),
           To_char(hire_date, 'DD-MON'),
           To_char(termination_date, 'DD-MON')
    INTO   employeeid, hiredate, terminationdate
    FROM   employees,
           time_sheet
    WHERE  employees.employee_id = time_sheet.employee_id
           AND paydate = pay_date;

    IF terminationdate > hiredate THEN
      RETURN 'T';
    ELSE
      IF To_char(SYSDATE, 'DD-MON') = To_char(hiredate, 'DD-MON')THEN
        RETURN 'Y';
      ELSE
        RETURN 'N';
      END IF;
    END IF;

    paydate := paydate + 1;
END LOOP;
END; 

Tables I am using

CREATE TABLE Employees ( EMPLOYEE_ID INTEGER,
FIRST_NAME VARCHAR2(15),
 LAST_NAME VARCHAR2(25),
 ADDRESS_LINE_ONE VARCHAR2(35),
 ADDRESS_LINE_TWO VARCHAR2(35),
 CITY VARCHAR2(28),
 STATE CHAR(2),
 ZIP_CODE CHAR(10),
 COUNTY VARCHAR2(10),
 EMAIL VARCHAR2(16),
 PHONE_NUMBER VARCHAR2(12),
 SOCIAL_SECURITY_NUMBER VARCHAR2(11),
 HIRE_DATE DATE,
 TERMINATION_DATE DATE,
 DATE_OF_BIRTH DATE,
 SPOUSE_ID INTEGER,
 MARITAL_STATUS CHAR(1),
  ALLOWANCES INTEGER,
  PERSONAL_TIME_OFF FLOAT,
  CONSTRAINT pk_employee_id PRIMARY KEY (EMPLOYEE_ID),
   CONSTRAINT fk_spouse_id FOREIGN KEY (SPOUSE_ID) REFERENCES EMPLOYEES (EMPLOYEE_ID))
 /
 CREATE TABLE Arndt_Raw_Time_Sheet_data ( EMPLOYEE_ID INTEGER,
    PAY_DATE DATE,
     HOURS_WORKED FLOAT,
     SALES_AMOUNT FLOAT,
      CONSTRAINT pk_employee_id_pay_date_time PRIMARY KEY (EMPLOYEE_ID, PAY_DATE),
      CONSTRAINT fk_employee_id_time FOREIGN KEY (EMPLOYEE_ID) REFERENCES EMPLOYEES (EMployee_ID));

error FUNCTION Calc_Anniversary compiled
Warning: execution completed with warning