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),
);
Related
Here are my tables. I need to check that the 'program' attribute referenced in StudentsBranch with the table Students and the table Branches is the same. How can I do it?
CREATE TABLE Programmes (
name VARCHAR(200) UNIQUE NOT NULL,
CONSTRAINT pk_Programmes PRIMARY KEY (name)
);
CREATE TABLE Students (
id NUMERIC(10,0) UNIQUE NOT NULL,
program VARCHAR(200) NOT NULL,
CONSTRAINT pk_Students PRIMARY KEY (idnr),
FOREIGN KEY (program) REFERENCES Programmes(name)
);
CREATE TABLE Branches (
name VARCHAR(200) UNIQUE NOT NULL,
program VARCHAR(200) NOT NULL,
CONSTRAINT pk_Branches PRIMARY KEY (name, program),
FOREIGN KEY (program) REFERENCES Programmes(name)
);
CREATE TABLE StudentsBranch (
student NUMERIC(10,0) NOT NULL,
program VARCHAR(200) NOT NULL,
branch VARCHAR(200) NOT NULL,
CONSTRAINT pk_StudentsBranch PRIMARY KEY (student),
/* Below how the foreign keys I think should be */
FOREIGN KEY (student, program) REFERENCES Students(idnr, program),
FOREIGN KEY (branch, program) REFERENCES Branches(name, program)
/* I need to add a constraint to verify that the 'program' in Students
* and the 'program' in Branches are equivalent. How?
*/
);
You can't write that constraint with that existing database model you have now.
The only way I see you could do it, is by changing the primary key of Students to (id, program):
CREATE TABLE Students (
id NUMERIC(10,0) UNIQUE NOT NULL,
program VARCHAR(200) NOT NULL,
CONSTRAINT pk_Students PRIMARY KEY (id, program),
FOREIGN KEY (program) REFERENCES Programmes(name)
);
Then the table StudentsBranch could naturally enforce both FKs with using the single column program, as in:
CREATE TABLE StudentsBranch (
student NUMERIC(10,0) NOT NULL,
program VARCHAR(200) NOT NULL,
branch VARCHAR(200) NOT NULL,
CONSTRAINT pk_StudentsBranch PRIMARY KEY (student),
FOREIGN KEY (student, program) REFERENCES Students (id, program),
FOREIGN KEY (branch, program) REFERENCES Branches (name, program)
);
It is always a good idea to have an numeric column of primary key and have primary key for every table.
Once you have primary key for every table you can referece primary key of a specific table and refere it as foerign key.
CREATE TABLE Programmes (
ID INT,
name VARCHAR(200) UNIQUE NOT NULL,
CONSTRAINT pk_Programmes PRIMARY KEY (ID)
);
CREATE TABLE Students(
id INT,
ProgrammID INT NOT NULL,
CONSTRAINT pk_Students PRIMARY KEY (ID),
FOREIGN KEY (ProgrammID) REFERENCES Programmes(ID)
);
CREATE TABLE Branches (
BranchID INT,
ProgrammID INT NOT NULL,
name VARCHAR(200) UNIQUE NOT NULL,
--program VARCHAR(200) NOT NULL,
CONSTRAINT pk_Branches PRIMARY KEY (BranchID, ProgrammID),
FOREIGN KEY (ProgrammID) REFERENCES Programmes(ID)
);
CREATE TABLE StudentsBranch (
StudentsBranchID INT,
studentID INT NOT NULL,
ProgrammID INT NOT NULL,
BranchID INT NOT NULL,
CONSTRAINT pk_StudentsBranch PRIMARY KEY (StudentsBranchID),
FOREIGN KEY (ProgrammID) REFERENCES Programmes(id),
FOREIGN KEY (studentID) REFERENCES Students(id),
FOREIGN KEY (BranchID, ProgrammID) REFERENCES Branches(BranchID, ProgrammID)
);
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 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 am starting to build something like system up to the just cooperate with suggestions coming into the database called ForslagOpslag.
Every time I try to update table with likes, you will see it with this one error:
Update cannot proceed due to validation errors. Please correct the following errors and try again.
SQL71516 :: The referenced table '[dbo].[ForslagOpslag]' contains no
primary or candidate keys that match the referencing column list in
the foreign key. If the referenced column is a computed column, it
should be persisted.
Here is how I built my ForslagOpslagLikes table:
CREATE TABLE [dbo].[ForslagOpslagLikes]
(
[fk_brugerid] INT NOT NULL,
[opretdato] DATETIME NOT NULL,
[getid] INT NOT NULL,
CONSTRAINT [PK_ForslagOpslagLikes]
PRIMARY KEY CLUSTERED ([fk_brugerid], [getid]),
CONSTRAINT [FK_ForslagOpslagLikes_ToGetid]
FOREIGN KEY ([getid])
REFERENCES [dbo].[ForslagOpslag]([Id]),
CONSTRAINT [FK_ForslagOpslagLikes_ToForslagBrugerid]
FOREIGN KEY ([fk_brugerid])
REFERENCES [dbo].[ForslagOpslag]([fk_brugerid])
);
Reason I have both fk_brugerid and getid is for sure me that the user can not vote / like more once!
The way I have built my ForslagOpslag table:
CREATE TABLE [dbo].[ForslagOpslag]
(
[Id] INT IDENTITY (1, 1) NOT NULL,
[text] NVARCHAR (MAX) NOT NULL,
[fk_brugerid] INT NOT NULL,
[opretdato] DATETIME NOT NULL,
PRIMARY KEY CLUSTERED ([Id] ASC)
);
like this to be my like system do:
ForslagOpslagLikes -> fk_brugerid to ForslagOpslag -> fk_brugerid
ForslagOpslagLikes -> getid to ForslagOpslag -> id
Well - the error seems pretty clear: you're trying to estabslish a foreign key relationship to ForslagOpslag.fk_brugerid here:
CONSTRAINT [FK_ForslagOpslagLikes_ToForslagBrugerid]
FOREIGN KEY ([fk_brugerid])
REFERENCES [dbo].[ForslagOpslag]([fk_brugerid])
but that column is NOT the primary key of that other table - and it's not a UNIQUE constraint either - so you cannot reference that column in a foreign key relationship.
But the column(s) that a foreign key references must be the primary key of that other table - or in SQL Server, it's good enough if there's a UNIQUE constraint on that column. You must ensure that the values you reference in FroslagOpslag only match a single column in that table - otherwise, you cannot establish a foreign key relationship
Try to remove the foreing key in your first table like this
CREATE TABLE [dbo].[ForslagOpslagLikes]
(
[fk_brugerid] INT NOT NULL,
[opretdato] DATETIME NOT NULL,
[getid] INT NOT NULL,
CONSTRAINT [PK_ForslagOpslagLikes]
PRIMARY KEY CLUSTERED ([fk_brugerid], [getid]),
CONSTRAINT [FK_ForslagOpslagLikes_ToGetid]
FOREIGN KEY ([getid])
REFERENCES [dbo].[ForslagOpslag]([Id]),
);
Then you need to add the foreign key in the second table with the primary key with the first table
CREATE TABLE [dbo].[ForslagOpslag]
(
[Id] INT IDENTITY (1, 1) NOT NULL,
[text] NVARCHAR (MAX) NOT NULL,
[fk_brugerid] INT NOT NULL,
[opretdato] DATETIME NOT NULL,
PRIMARY KEY CLUSTERED ([Id] ASC),
CONSTRAINT [FK_ForslagOpslagLikes_ToForslagBrugerid]
FOREIGN KEY ([fk_brugerid])
REFERENCES [dbo].[ForslagOpslagLikes]([fk_brugerid])
);
You sound scandinavian, and Bruger means User (for all the non-scandinavians here).
What you appear to want is a Bruger (User) table, where fk_brugerid in ForslagOpslag is the user who created the record with opretdato being the creation date, and ForslagOpslagLikes is an association table of users who likes the ForslagOpslag with opretdato being the date they clicked on "Like".
CREATE TABLE [dbo].[Bruger]
(
[brugerid] INT IDENTITY (1, 1) NOT NULL,
...,
CONSTRAINT [PK_Bruger]
PRIMARY KEY CLUSTERED ([brugerid])
);
CREATE TABLE [dbo].[ForslagOpslag]
(
[Id] INT IDENTITY (1, 1) NOT NULL,
[text] NVARCHAR(MAX) NOT NULL,
[fk_brugerid] INT NOT NULL,
[opretdato] DATETIME NOT NULL,
CONSTRAINT [PK_ForslagOpslag]
PRIMARY KEY CLUSTERED ([Id]),
CONSTRAINT [FK_ForslagOpslag_Bruger]
FOREIGN KEY ([fk_brugerid])
REFERENCES [dbo].[Bruger] ([brugerid])
);
CREATE TABLE [dbo].[ForslagOpslagLikes]
(
[fk_brugerid] INT NOT NULL,
[opretdato] DATETIME NOT NULL,
[getid] INT NOT NULL,
CONSTRAINT [PK_ForslagOpslagLikes]
PRIMARY KEY CLUSTERED ([fk_brugerid], [getid]),
CONSTRAINT [FK_ForslagOpslagLikes_Bruger]
FOREIGN KEY ([fk_brugerid])
REFERENCES [dbo].[Bruger] ([brugerid]),
CONSTRAINT [FK_ForslagOpslagLikes_ForslagOpslag]
FOREIGN KEY ([getid])
REFERENCES [dbo].[ForslagOpslag]([Id])
);
CREATE TABLE Review(
VersionID VARCHAR(5) PRIMARY KEY NOT NULL,
rating INT,
FOREIGN KEY (PaperID) REFERENCES Paper(PaperID),
FOREIGN KEY (Revi) REFERENCES Paper(PaperID)
);
You should do it this way:
CREATE TABLE Review(
VersionID VARCHAR(5) PRIMARY KEY NOT NULL,
rating INT,
constraint constraint_1_name FOREIGN KEY (PaperID) REFERENCES Paper(PaperID),
constraint constraint_2_name FOREIGN KEY (Revi) REFERENCES Paper(PaperID)
);
(Of course instead of paperId/Revi you should use existing field names...)