Here is the code I'm using in Oracle SQL Developer :
CREATE TABLE ORDER_ITEMS(
ITEM_NO NUMBER(10),
ITEM_DESCRIPTION VARCHAR(50),
SIZE VARCHAR(5),
COST NUMBER(8,2),
QUANTITY NUMBER(10),
TOTAL NUMBER(8,2),
ITEM_ORDER_NO NUMBER(10),
CONSTRAINT ITM_NO_PK PRIMARY KEY (ITEM_NO));
The error has to do with the SIZE and COST tables, if I change the names on those two tables (for example put an A at the end of them (SIZEA COSTA)) then the code works. Why are these table names invalid ?
I think you mean column where you're writing table. Also SIZE is a reserved word in Oracle SQL, as is NUMBER.
https://docs.oracle.com/cd/B19306_01/server.102/b14200/ap_keywd.htm
Related
CREATE TABLE Route(
RouteNo VARCHAR(10),
Origin VARCHAR(30),
Destination VARCHAR(30),
DepartureTime VARCHAR(15),
SerialNo VARCHAR(5),
ArrivalTime VARCHAR(15),
PRIMARY KEY(RouteNo) );
CREATE TABLE Employee(
EmployeeID VARCHAR(5) NOT NULL,
Name VARCHAR(30),
Phone NUMBER,
JobTitle VARCHAR(30),
PRIMARY KEY(EmployeeID) );
CREATE TABLE Flight(
SerialNo VARCHAR(5),
RouteNo VARCHAR(5),
FlightDate DATE,
ActualTD VARCHAR(10),
ActualTA VARCHAR(10),
PRIMARY KEY(SerialNo, RouteNo, FlightDate),
FOREIGN KEY(RouteNo) REFERENCES Route(RouteNo),
FOREIGN KEY(SerialNo) REFERENCES Airplane(SerialNo) ); -- does Airplane table exists ?
CREATE TABLE CrewAssigment(
EmployeeID VARCHAR(5),
RouteNo VARCHAR(5),
FlightDate DATE,
Role VARCHAR(45),
Hours INT,
PRIMARY KEY(EmployeeID, RouteNo, FlightDate),
FOREIGN KEY(EmployeeID) REFERENCES Employee(EmployeeID),
FOREIGN KEY(RouteNo) REFERENCES Route(RouteNo),
FOREIGN KEY(FlightDate) REFERENCES Flight(FlightDate) );
Select * from CrewAssignment
This is my code where I'm getting an error in the CrewAssignment table and above are the tables where the foreign key is referenced from.
Error report -
ORA-02270: no matching unique or primary key for this column-list
02270. 00000 - "no matching unique or primary key for this column-list"
*Cause: A REFERENCES clause in a CREATE/ALTER TABLE statement
gives a column-list for which there is no matching unique or primary
key constraint in the referenced table.
*Action: Find the correct column names using the ALL_CONS_COLUMNS
catalog view
A few objections.
This is clearly an Oracle question, not MySQL. How do I know? ORA-02270 is an Oracle database error code; pay attention to tags you use.
You should use VARCHAR2 datatype instead of VARCHAR. Why? Oracle recommends so.
create table flight fails first as it references the airplane table, and it doesn't exist yet (at least, not in code you posted)
error you're complaining about is due to create table crewassignment. One of its foreign keys references the flight table:
FOREIGN KEY(flightdate) REFERENCES flight(flightdate)
but flight's primary key is composite, made up of 3 columns:
PRIMARY KEY(serialno,
routeno,
flightdate)
which means that you can't create that foreign key.
So, what to do? No idea, I don't know rules responsible for such a data model. Either modify primary key of the flight table, or modify foreign key constraint of the crewassingment table.
Perhaps you could add a new column to flight table (made up of a sequence (or identity column, if your database version supports it) and then let the crewassignment table reference that primary key. Columns you currently use as a primary key (serialno, routeno, flightdate) would then switch to unique key.
I've got a hierarchy pretty similar to this one in an Oracle Database
CREATE TYPE PersonUdt AS OBJECT(
personId number(10),
Name varchar(20)
)INSTANTIABLE NOT FINAL;
CREATE OR REPLACE TYPE PatientUdt under PersonUdt(
insurancePlan varchar(100)
);
CREATE OR REPLACE TYPE DoctorUdt under PersonUdt(
area varchar(20)
);
CREATE TABLE Person of PersonUdt(
personId PRIMARY KEY
)OBJECT IDENTIFIER IS SYSTEM GENERATED;
I've got some insertions on the table,like
INSERT INTO person VALUES(DoctorUdt(1, 'Alfred', 'Area One'));
I would like to create a constraint to limit the area in which the a doctor can work. Let's say, limit it to Area one, two and three.
Is it possible to do this using ALTER TABLE x ADD CONSTRAINT... functions?
Thanks in advance!
I'm wondering is it possible to use a constraint to set the value of one column to be sum of two others. For example given the following tables:
CREATE TABLE Room (
Room_Num NUMBER(3),
Room_Band_ID NUMBER(2),
Room_Type_ID NUMBER(2),
Room_Price NUMBER(4),
PRIMARY KEY (Room_Num),
FOREIGN KEY(Room_Band_ID)
REFERENCES Room_Band(Room_Band_ID),
FOREIGN KEY(Room_Type_ID)
REFERENCES Room_Type(Room_Type_ID)
);
CREATE TABLE Booking (
Booking_ID NUMBER(10) NOT NULL,
GuestID NUMBER(4) NOT NULL,
StaffID NUMBER(2) NOT NULL,
Payment_ID NUMBER(4) NOT NULL,
Room_Num NUMBER(3) NOT NULL,
CheckInDate DATE NOT NULL,
CheckOutDate DATE NOT NULL,
Booking NUMBER(2) NOT NULL,
Price NUMBER(4),
PRIMARY KEY (Booking_ID),
FOREIGN KEY(GuestID)
REFERENCES Guest(GuestID),
FOREIGN KEY(StaffID)
REFERENCES Staff(StaffID),
FOREIGN KEY(Payment_ID)
REFERENCES Payment(Payment_ID),
FOREIGN KEY(Room_Num)
REFERENCES Room(Room_Num)
);
I know it is possible to do something like:
Constraint PriceIs CHECK (Booking.Price=(Room.Room_Price*
(Booking.CheckOutDate - Booking.CheckInDate)));
Is it also possible to set up a constraint that doesn't just ensure that the price is correct, but to calculate the price automatically into the price field for the relevant tuple?
Update,
So I've tried to set up a trigger as follows:
CREATE OR REPLACE trigger PriceCompute
AFTER INSERT ON Booking
FOR each row
BEGIN
UPDATE Booking
SET
SELECT (Room.Room_Price*(Booking.CheckOutDate - Booking.CheckInDate))
INTO
Booking.Price
FROM Booking
JOIN ROOM ON Booking.Room_Num = Room.Room_Num
END;
/
But I'm getting the following errors back:
Can anyone see where I'm going astray here, as its beyond me.
Yes, you can. Here are your options. Listed in order of my personal preference:
You can have a table without this column. And create a view that will be calculating this column on a fly.
You may use oracle virtual columns
create table Room (
...
price NUMBER GENERATED ALWAYS AS (room_price*(checkOut-checkIn)) VIRTUAL,
...)
You may use actual column (same as 2, per Dave Costa):
create table Room (
...
price AS (room_price*(checkOut-checkIn)),
...)
You can write trigger to populate it (like Mat M suggested)
You can write stored procedure, but it will be an overkill in this situation
I think you would have to put a trigger on both tables for whenever the price value of the room is changed or the checkout/in dates are changed, it will update the PriceIs field from your calculation.
If you don't need the calculated portion stored in an actual field, you can always create a view that calculates it whenever you look at the view.
I think the better solution is to use a view that calculates the value on the fly. But regarding your attempt to create a trigger, you should use :new.<column_name> to refer to the values being inserted into the Booking table. You don't need to perform updates and queries on that table to get or modify the values in the row that is being inserted*. You just refer to them as variables. So you would want to do something like:
SELECT (Room.Room_Price*(:new.CheckOutDate - :new.CheckInDate))
INTO
:new.Price
FROM ROOM WHERE :new.Room_Num = Room.Room_Num
*In fact, you can't perform queries or updates on the table whose modification invoked the trigger in the first place. You would get the infamous "mutating table" error if your trigger actually compiled and ran.
I got the following sql:
create or replace type MEDIUM_TYPE AS OBJECT
(
me_movie REF MOVIE_TYPE,
me_rating varchar2(2),
me_runtime number(3,0),
me_release_year number(4,0),
me_list_price number(3,2),
me_our_price number(3,2),
me_availability varchar2(128),
me_aspect_ratio varchar2(8),
me_encoding number (1,0),
me_subtitle_language SUBTITLE_LANGUAGE_TYPE,
me_number_of_discs number (1,0)
)not final
/
create table DVD of MEDIUM_TYPE
object id system generated
/
How can i make sure that me_movie in the dvd table is unique?
And also, how can i do something like this?
mo_release_year number(4,0) BETWEEN 1900 AND 2100,
It's pretty much the same syntax as for relational tables:
create table DVD of MEDIUM_TYPE
( me_movie primary key )
object id system generated
/
The one problem you have is that you will run into this error:
ORA-02329: column of datatype REF cannot be unique or a primary key
Which admittedly is a bit of a showstopper. You will need to re-think your whole model. Sorry about that.
Is it possible to set a unique constraint as a foreign key in another table?
If yes, how would you go about declaring it?
How would you go about assigning a candidate key?
Is it possible?
Example:
I have a product table that consists of:
prod_id, prod_name, prod_price, QOH
Where I want prod_name to link to the despatch table:
desp_id, prod_name, shelfLoc, quantity
What I was thinking is that I may need to create a unique constraint which will look like this:
ALTER TABLE product
ADD CONSTRAINT prod_nameID_uc
UNIQUE (prod_id,prod_name)
What I'm wondering is, if it is possible to refer to a unique key as a foreign key in the despatch table. I have to have prod_name rather than prod_id in the despatch table so that the information is more meaningful to the user when reading it, rather than seeing an id number.
I am using iSQL plus on oracle.
It is perfectly possible to reference a UNIQUE constraint in an Oracle FOREIGN KEY:
SQL> create table products (
2 prod_id number not null
3 , prod_name varchar2 (30) not null
4 , constraint prod_pk primary key ( prod_id )
5 , constraint prod_uk unique ( prod_name )
6 )
7 /
Table created.
SQL> create table despatch (
2 desp_id number not null
3 , prod_name
4 , constraint desp_pk primary key ( desp_id )
5 , constraint desp_prod_pk foreign key ( prod_name )
6 references products ( prod_name )
7 )
8 /
Table created.
SQL>
It is however bad practice. The main reason for using a primary key alongside a unique key is to provide a synthetic key for use in foreign keys. I were you I would be concerned that your teachers are giving you an assignment riddled with bad practice.
This is necessarily DBMS dependent. In the DBMSes I'm familiar with, the unique constraint and the foreign key constraint are separate considerations, you can have both, and they both act normally when combined.