Insert fails due to "column not allowed here" error

Question

I am a beginner with SQL. I have created 4 tables and added data to my SHIP table. I am having some issues with inserting data into the CRUISE table. I get the error message at the bottom.

I have researched and can not figure out what i am doing wrong. Is there an issue with my sequence and/or trigger that is not allowing me to do this or is my syntax in the CREATE TABLE CRUISE causing the error? Everything i have done has been successful up until trying to insert the first column into the CRUISE table.

The tables:

CREATE TABLE SHIP 
( Ship_Name VARCHAR2(100) PRIMARY KEY,
Ship_Size INTEGER,
Ship_Registry VARCHAR2(50),
Ship_ServEntryDate INTEGER,
Ship_PassCapacity INTEGER,
Ship_CrewCapacity INTEGER,
Ship_Lifestyle VARCHAR2(40),
CONSTRAINT Size_ck CHECK (Ship_Size > 0),
CONSTRAINT Registry_ck CHECK (Ship_Registry IN ('Norway','Liberia','The Netherlands','Bahamas'))
)

CREATE TABLE CRUISE (
Cruise_ID INTEGER Primary Key,
Ship_Name VARCHAR(100),
Cruise_DeptDate DATE NOT NULL,
Cruise_DeptCity VARCHAR(80) NOT NULL,
Cruise_Duration INTEGER,
FOREIGN KEY (Ship_Name) REFERENCES SHIP(Ship_Name)
)

CREATE TABLE PASSENGERS (
Pass_ID INTEGER PRIMARY KEY,
Pass_Name VARCHAR(100) NOT NULL,
Pass_City VARCHAR(80),
Pass_Telephone VARCHAR(15),
Pass_NextOfKin VARCHAR(100)
)

CREATE TABLE RESERVATIONS (
Pass_ID INTEGER NOT NULL,
Cruise_ID INTEGER NOT NULL,
Res_TotalCost NUMERIC(9,2),
Res_BalanceDue NUMERIC(9,2),
Res_SpecialRequest VARCHAR(30),
Res_Room VARCHAR(10),
FOREIGN KEY (Pass_ID) REFERENCES PASSENGERS(Pass_ID),
FOREIGN KEY (Cruise_ID) REFERENCES CRUISE(Cruise_ID),
CONSTRAINT Cost_ck CHECK (Res_TotalCost >= 0),
CONSTRAINT BalanceDue_ck CHECK (Res_BalanceDue >= 0),
CONSTRAINT SpecialRequest_ck CHECK (Res_SpecialRequest IN ('Vegetarian','Vegan','Low salt','Gluten free','Kosher','Other'))
)

The sequence/trigger is an attempt to auto number Cruise_ID.

Create SEQUENCE cruise_id_sq
START WITH 1
INCREMENT BY 1;

CREATE OR REPLACE TRIGGER cruise_id_t
BEFORE INSERT 
ON CRUISE
REFERENCING NEW AS NEW
FOR EACH ROW
BEGIN
if(:new.Cruise_ID is null) then
SELECT cruise_id_sq.nextval
INTO :new.Cruise_ID
FROM dual;
end if;
END;

ALTER TRIGGER cruise_id_t ENABLE;

Inserting into SHIP is okay....

INSERT INTO SHIP
(Ship_Name, Ship_Size, Ship_Registry,Ship_ServEntryDate, Ship_PassCapacity,Ship_CrewCapacity,Ship_Lifestyle)
Values ('Carribean Princess',142000,'Liberia',1000,3100,1181,'Contemporary');

INSERT INTO SHIP
(Ship_Name, Ship_Size, Ship_Registry,Ship_ServEntryDate, Ship_PassCapacity,Ship_CrewCapacity,Ship_Lifestyle)
Values ('Carribean Sunshine',74000,'Norway',1992,1950,760,'Premium');

INSERT INTO SHIP
(Ship_Name, Ship_Size, Ship_Registry,Ship_ServEntryDate, Ship_PassCapacity,Ship_CrewCapacity,Ship_Lifestyle)
Values ('Ship of Dreams',70000,'Liberia',2004,1804,735,'Contemporary');

INSERT INTO SHIP
(Ship_Name, Ship_Size, Ship_Registry,Ship_ServEntryDate, Ship_PassCapacity,Ship_CrewCapacity,Ship_Lifestyle)
Values ('Sunshine of the Seas',74000,'The Netherlands',1990,2354,822,'Luxury');

Inserting into CRUISE fails...

INSERT INTO Cruise
(Ship_Name, Cruise_DeptDate,Cruise_DeptCity,CruiseDuration)
Values ('Sunshine of the Seas',25-may-15,'Miami',10);

Error starting at line : 1 in command - INSERT INTO Cruise (Ship_Name, Cruise_DeptDate,Cruise_DeptCity,CruiseDuration) Values ('Sunshine of the Seas',25-may-15,'Miami',10) Error at Command Line : 3 Column : 35 Error report - SQL Error: ORA-00984: column not allowed here 00984. 00000 - "column not allowed here" *Cause:
*Action:

Answer 1

Oracle thinks that 25-may-15 is the expression 25 minus may minus 15. In looking up the value for may Oracle finds that there is nothing there. Thus the error.

You can, but probably don't want to, quote it like so, '25-may-15'. This will make a string that may or may not be implicitly converted to a date, depending on the settings of NLS_DATE_FORMAT and or NLS_TERRITORY.

To form a date independent of session setting one can use the TO_DATE function with explicit date format, to_date('25-may-15', 'DD-Mon-YY'). Another option is a date literal, date '2015-05-25', which is always YYYY-MM-DD no matter the session settings..