I have the following queries that I run to create tables in MS SQL Server:
CREATE TABLE menus
(
menu_id int NOT NULL PRIMARY KEY,
menu_name char,
other_details char
)
CREATE TABLE bookings
(
booking_Id int NOT NULL PRIMARY KEY,
date_booked DATE,
date_of_booking DATE,
other_details char,
staff_id int FOREIGN KEY REFERENCES staff(staff_id),
customer_id int FOREIGN KEY REFERENCES customers(customer_id)
)
CREATE TABLE menus_booked
(
menu_id INT NOT NULL,
booking_id INT NOT NULL,
CONSTRAINT PK_menus_booked PRIMARY KEY(menu_id,booking_id),
FOREIGN KEY (menu_id) REFERENCES menus(menu_id),
FOREIGN KEY (booking_id) REFERENCES bookings(booking_id)
)
CREATE TABLE menu_changes
(
change_id int NOT NULL PRIMARY KEY,
menu_id int NOT NULL,
booking_id int NOT NULL,
change_details char,
FOREIGN KEY (menu_id) REFERENCES menus_booked(menu_id),
FOREIGN KEY (booking_id) REFERENCES menus_booked(booking_id)
)
On running the last query I get the error:
There are no primary or candidate keys in the referenced table 'menus_booked' that match the referencing column list in the foreign key 'FK_menu_chan_menu'
I am unsure if my queries are correct and can't resolve this error.
The primary key of menus_booked is a unique combination of menu_id and booking_id. A foreign must point to that combination, not just one of its fields, which is not necessarily unique. Your query currently tries to define two foreign keys, one on each column, instead of one foreign key on the combination of the columns:
CREATE TABLE menu_changes
(
change_id int NOT NULL PRIMARY KEY,
menu_id int NOT NULL,
booking_id int NOT NULL,
change_details char,
FOREIGN KEY (menu_id, booking_id)
REFERENCES menus_booked(menu_id, booking_id) -- Here!
)
A foreign key has to reference a primary key (or unique key but here the PK is the problem), and it has to reference it in it's entirety.
FOREIGN KEY (menu_id) REFERENCES menus_booked(menu_id),
FOREIGN KEY (booking_id) REFERENCES menus_booked(booking_id)
You have two foreign key's referencing part of the primary key of menus_booked. You'll have to alter it to:
FOREIGN KEY (menu_id, booking_id) REFERENCES menus_booked(menu_id, booking_id)
Related
Whenever I try to create these two tables in oracle live SQL it gives right parenthesis error.
CREATE TABLE Section_Table (
Status_ID INT Primary Key,
Names varchar(20),
course_id int FOREIGN KEY references Course_Table(course_id),
Schedule_id int FOREIGN KEY references Schedule_Table(Schedule_id),
Instruction_id int
);
CREATE TABLE Enrollment_Table (
ENROLLMENT_ID INT PRIMARY KEY,
STUDENT varchar(20),
course_id INT FOREIGN KEY REFERENCES Course_Table(course_id),
LEVEL_ID INT FOREIGN KEY REFERENCES Level_Table(LEVEL_ID),
Status_id INT FOREIGN KEY REFERENCES Status_Table(Status_ID),
DATE_ENROLLED DATE
);
I am unable to find an error in this code, it shows ORA-00907: missing right parenthesis for both. I'm doing this on Oracle live SQL.
CREATE table Final_chart
(
T_id int FOREIGN KEY REFERENCES Train(T_id),
User_id varchar(10) FOREIGN KEY REFERENCES Passenger(User_id),
Seat_id int FOREIGN KEY REFERENCES Train_Seats(Seat_id),
CONSTRAINT PNR PRIMARY KEY (T_id,User_id,Seat_id)
)
CREATE table Train_seats
(
T_id int FOREIGN KEY REFERENCES Train(T_id),
Seat_id int PRIMARY KEY,
Waiting int NOT NULL,
Available int NOT NULL,
Booked_seat int NOT NULL
)
Working example for one table. And please use varchar2 instead on varchar in oracle.
CREATE table Final_chart
(T_id integer,
User_id varchar2(10),
Seat_id integer,
CONSTRAINT t2_fk FOREIGN KEY (T_id) REFERENCES Train(T_id),
CONSTRAINT t1_fk FOREIGN KEY (User_id) REFERENCES Passenger(User_id),
CONSTRAINT t3_fk FOREIGN KEY (Seat_id) REFERENCES Train_Seats(Seat_id),
CONSTRAINT Pkr PRIMARY KEY (T_id, User_id, Seat_id)
)
The problem is your reference to the foreign key. this is the way you should do it
CONSTRAINT FK_Train FOREIGN KEY (T_id) REFERENCES Train(T_id)
How can I make an attribute a primary key within a table but also as a foreign key which references another table using sql in sql developer?
I know how to make it an attribute as a foreign key and a primary separate but not as a primary key as well as a foreign key
That's perfectly normal. For example:
create table employee (
id number(6) primary key not null,
name varchar2(50)
);
create table employee_desk (
desk_id number(6) primary key not null, -- PK and FK!
location varchar2(20),
constraint fk1 foreign key (desk_id) references employee (id)
);
The column desk_id is the primary key of the table employee_desk, and also a foreign key that points to the table employee.
Below is the example of primary key with foreign key
create table animals (id integer primary key);
create table cats (
id integer primary key
, name varchar(100) not null
, constraint d_cats_animals_fk foreign key (id) references animals (id)
);
I'm getting this error when trying to create a table with foreign key:
There are no primary or candidate keys in the referenced table 'TeamToPlayers' that match the referencing column list in the foreign key 'FKey2'.
I don't understand why, there is a primary key in the table TeamToPlayers.
Here are the queries:
create table TeamToPlayers
(TeamName varchar(50) NOT NULL,
PlayerName varchar(50) NOT NULL,
primary key(TeamName,PlayerName),
CONSTRAINT FKey FOREIGN KEY (TeamName) REFERENCES Teams(TeamName)
)
create table Players
(PlayerName varchar(50) NOT NULL,
primary key(PlayerName),
CONSTRAINT FKey2 FOREIGN KEY (PlayerName) REFERENCES TeamToPlayers(PlayerName)
);
Table TeamToPlayers primary key consists of two fields - you must reference both as otherwise it's not a key. I think you may have your key the wrong way round - it should be on TeamToPlayers and referencing Players like so:
create table TeamToPlayers
(
TeamName varchar(50) NOT NULL,
PlayerName varchar(50) NOT NULL,
primary key(TeamName,PlayerName),
CONSTRAINT FKey FOREIGN KEY (TeamName) REFERENCES Teams(TeamName),
CONSTRAINT FKey2 FOREIGN KEY (PlayerName) REFERENCES Players(PlayerName)
)
create table Players
(PlayerName varchar(50) NOT NULL,
primary key(PlayerName),
);
If I declare the table below does it implicitly imply that both the foreign keys make a unique primary key or do I need to do something more to make both attributes as a primary key?
CREATE TABLE Report_has_Items
(
ReportID int REFERENCES Report(ReportID) NOT NULL,
ItemID int REFERENCES Item(ItemID) NOT NULL
)
Essentially both attributes which are foreign keys from other tables, together would form a unique key.
No it doesn't. The above table has no primary key. If you want to use the fields as a primary key use:
CREATE TABLE Report_has_Items(
ReportID int REFERENCES Report(ReportID) NOT NULL,
ItemID int REFERENCES Item(ItemID) NOT NULL,
PRIMARY KEY (ReportID, ItemID)
)
or something similar depending on your sql dilect.
Let's name our constraints, eh?
CREATE TABLE dbo.Report_has_Items(
ReportID int NOT NULL,
CONSTRAINT [FK_RHI_Report] (ReportId) REFERENCES dbo.Report(ReportID),
ItemID int NOT NULL,
Constraint [FK_RHI_Item] (ItemId) REFERENCES dbo.Item(ItemID),
CONSTRAINT [PK_RHI] PRIMARY KEY (ReportID, ItemID)
)
I am not sure i understand your question completely but i assume you are trying to create a composite primary key (primary key with more than one attribute). You could do the following.
CREATE TABLE Report_has_Items(
ReportID int references Report(ReportID),
ItemID int references Item(ItemID),
PRIMARY KEY (ReportID , ItemID )
);
Note:The pair (ReportID , ItemID ) must then be unique for the table and neither value can be NULL.
Here is a very useful link for SQL Queries