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)
);
Related
I'm trying to created a table, and give as a primary key, the 3 attributes, which it have.
The code is below:
CREATE TABLE compra
(
dni_cli VARCHAR2(50),
cod_prod NUMBER(10) NOT NULL,
cantidad NUMBER (10),
CONSTRAINT pk_compra PRIMARY KEY (dni_cli, cod_prod, cantidad);
CONSTRAINT pelicula_codigo_prod_fg FOREIGN KEY (cod_prod) REFERENCES producto(cod_prod),
CONSTRAINT pelicula_codigo_cli_fg FOREIGN KEY (dni_cli) REFERENCES cliente(dni)
);
I also tried to create the table first, and then, add the constraint in order to create the combined PRIMARY KEY with the alter table, but is doesn't work.
The code is this:
ALTER TABLE CONSTRAINT pk_compra PRIMARY KEY (dni_cli, cod_prod, cantidad);
If the primary key already exists you need to drop the key:
ALTER TABLE compra drop constraint pk_compra;
then add the key:
ALTER TABLE compra add constraint pk_compra primary key (city_id, buildtime, time);
If the primary key does not exist in the table then just use the second command line.
Also as #stickybit noted your table has an error. This is the code without an error:
CREATE TABLE compra (
dni_cli VARCHAR2(50),
cod_prod NUMBER(10) NOT NULL,
cantidad NUMBER (10),
CONSTRAINT pk_compra PRIMARY KEY (dni_cli,cod_prod,cantidad), --<<change here
CONSTRAINT pelicula_codigo_prod_fg FOREIGN KEY (cod_prod) REFERENCES producto(cod_prod),
CONSTRAINT pelicula_codigo_cli_fg FOREIGN KEY (dni_cli) REFERENCES cliente(dni));
I'm in the process of building a database and have already successfully created 2 primary key tables however when I try to bring them in as 2 foreign keys to another table I am running into a
"CLIENTID" invalid identifier
Unsure how to resolve as not the best at this.
CREATE TABLE Booking(
BookingID number(10) NOT NULL,
CONSTRAINT Client_FK FOREIGN KEY (ClientID) REFERENCES client (ClientID),
CONSTRAINT Course_FK FOREIGN KEY (CourseID) REFERENCES course (CourseID),
CONSTRAINT Booking_PK PRIMARY KEY (ClientID, CourseID)
);
You are missing the columns on which your primary key and foreign keys are created; you need something like the following, to be edited with the right type for your columns:
CREATE TABLE Booking(
BookingID number(10) NOT NULL,
ClientId number, -- missing
CourseID number, -- missing
CONSTRAINT Client_FK FOREIGN KEY (ClientID) REFERENCES client (ClientID),
CONSTRAINT Course_FK FOREIGN KEY (CourseID) REFERENCES course (CourseID),
CONSTRAINT Booking_PK PRIMARY KEY (ClientID, CourseID)
)
I am pretty new to SQL and I have a problem. I want to make a recursive relationship (a table that relates to itself), but I get an error when I try to execute my code. It's working fine without the Coordinator_Office_ID foreign key.
The error is:
The number of columns in the foreign-key referencing list is not equal
to the number of columns in the referenced list.
Create table Logistican (
Office_ID Number(10) Constraint nb_office Not NULL,
Worker_ID Number(15) Constraint lg_worker not null,
Name_logistican Varchar(20),
Room Varchar(10) constraint log_room UNIQUE,
Coordinator_Office_ID Integer,
Primary key (Office_ID, Worker_ID),
Constraint work_id Foreign key (Worker_ID) References worker(worker_ID) on delete cascade,
Constraint lg_cord_id Foreign key (Coordinator_Office_ID) References Logistican(Office_ID)
);
Yes, that's cause you have defined composite primary key like Primary key (Office_ID, Worker_ID) and thus your FK should include both of them else it will result in PFD (partial functional dependency)
Add the constraint with alter table:
Create table Logistican (
Office_ID Number(10) Constraint nb_office Not NULL,
Worker_ID Number(15) Constraint lg_worker not null,
Name_logistican Varchar(20),
Room Varchar(10) constraint log_room UNIQUE,
Coordinator_Office_ID Integer,
Primary key (Office_ID, Worker_ID),
Constraint work_id Foreign key (Worker_ID) References worker(worker_ID) on delete cascade
);
alter table Logistican
add Constraint lg_cord_id
Foreign key (Coordinator_Office_ID, Worker_Id) References Logistican(Office_ID, Worker_Id);
The relationship needs all elements of the primary key to be valid. I'm not sure if it needs to be a separate statement in Oracle.
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)
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),
);