I cant find a good anwser too my question, I want to create a table that have references too one table but i use it twice in the code..
Vårdnadshavare VARCHAR(11),
FOREIGN KEY (Vårdnadshavare) REFERENCES Person(Personnummer),
Barn VARCHAR(11),
FOREIGN KEY (Barn) REFERENCES Person(Personnummer)
But then i get the error:
ORA-02256: number of referencing columns must match referenced columns
I understand that my reference is wrong some how but can´t figure it out...
Sorry for the swedish words!!
Create table Ärende(
Ärendenr VARCHAR(50) NOT NULL,
Handläggare VARCHAR(50),
FOREIGN KEY (Handläggare) REFERENCES Handläggare(Anställningsnr),
Vårdnadshavare VARCHAR(11),
FOREIGN KEY (Vårdnadshavare) REFERENCES Person(Personnummer),
Barn VARCHAR(11),
FOREIGN KEY (Barn) REFERENCES Person(Personnummer),
In Datum VARCHAR(50),
Ömmande Skäl VARCHAR(5),
Förskola VARCHAR(50),
FOREIGN KEY (Förskola) REFERENCES Förskola(IDnr),
PRIMARY KEY (Ärendenr)
);
I have used Person(Personnumer) as a reference before just not twice in createing a table..
I created this script which does work. Probably there is an issue with your indexes:
create table handläggare
( anställningsnr varchar(50) primary key
)
create table person
( personnummer varchar(11) primary key
)
;
create table förskola
( idnr varchar(50) primary key
);
create table ärende
( ärendenr varchar(50) not null
, handläggare varchar(50)
, foreign key (handläggare) references handläggare(anställningsnr)
, vårdnadshavare varchar(11)
, foreign key (vårdnadshavare) references person(personnummer)
, barn varchar(11)
, foreign key (barn) references person(personnummer)
, indatum varchar(50)
, ömmandeskäl varchar(5)
, förskola varchar(50)
, foreign key (förskola) references förskola(idnr)
, primary key (ärendenr)
);
There are two other issues in your script above which I edited:
In Datum should be one name, not separated by a space;
Ömmande Skäl, same as above.
In you create statement you have provided 4 referenes:
Handläggare VARCHAR(50),
FOREIGN KEY (Handläggare) REFERENCES Handläggare(Anställningsnr),
Vårdnadshavare VARCHAR(11),
FOREIGN KEY (Vårdnadshavare) REFERENCES Person(Personnummer),
Barn VARCHAR(11),
FOREIGN KEY (Barn) REFERENCES Person(Personnummer),
Förskola VARCHAR(50),
FOREIGN KEY (Förskola) REFERENCES Förskola(IDnr),
Please check that all 3 distinct columns are of same data type.
That means:
Handläggare(Anställningsnr) should be VARCHAR(50)
Person(Personnummer) should be VARCHAR(11)
Förskola(IDnr) should be VARCHAR(50).
As per me i think you are making a mistake in
Förskola(IDnr) should be VARCHAR(50)
which should have been a Number
Related
I'm a beginner learning SQL and am having trouble implementing this concept.
Suppose you create the following three tables:
CREATE TABLE dogOwner(
ownerNo VARCHAR(8) CONSTRAINT ownerNo_pk1 PRIMARY KEY,
ownerName VARCHAR(10)
);
CREATE TABLE catOwner(
ownerNo VARCHAR(8) CONSTRAINT ownerNo_pk2 PRIMARY KEY,
ownerName VARCHAR(10)
);
CREATE TABLE petsAdopted(
petNo VARCHAR(8) CONSTRAINT petNo_pk PRIMARY KEY,
ownerNo VARCHAR(8) CONSTRAINT ownerNo_fk1 REFERENCES dogOwner(ownerNo)
CONSTRAINT ownerNo_fk2 REFERENCES catOwner(ownerNo)
);
How do you properly create constraints for the foreign key ownerNo, which references ownerNo from two other tables?
You can't. You could have 2 columns in petsAdopted: dogOwnerNo and catOwnerNo and 2 foreign keys. But the table design doesn't seem to make sense: surely a pet either is a dog or a cat (or something else) regardless of who owns it?
Here is an alternative design:
CREATE TABLE owner(
ownerNo VARCHAR(8) CONSTRAINT ownerNo_pk2 PRIMARY KEY,
ownerName VARCHAR(10)
);
CREATE TABLE petsAdopted(
petNo VARCHAR(8) CONSTRAINT petNo_pk PRIMARY KEY,
petType VARCHAR2(10) NOT NULL CONSTRAINT petTypeChk (CHECK petType in ('CAT','DOG'))
ownerNo VARCHAR(8) CONSTRAINT ownerNo_fk REFERENCES owner(ownerNo)
);
This only address syntax part of your answer which You have got lot of syntax error, but this will not work, Please rethink your design.
CREATE TABLE dogOwner(
ownerNo VARCHAR(8) CONSTRAINT ownerNo_pk1 PRIMARY KEY,
ownerName VARCHAR(10)
);
CREATE TABLE catOwner(
ownerNo VARCHAR(8),
ownerName VARCHAR(10),
CONSTRAINT ownerNo_pk2 PRIMARY KEY (ownerNo),
CONSTRAINT ownerNo_fk1 FOREIGN KEY (ownerNo) REFERENCES dogOwner(ownerNo)
);
CREATE TABLE petsAdopted(
petNo VARCHAR(8) ,
ownerNo VARCHAR(8),
CONSTRAINT petNo_pk PRIMARY KEY (petNo),
CONSTRAINT ownerNo_fk_pet1 FOREIGN KEY (ownerNo) REFERENCES dogOwner(ownerNo),
CONSTRAINT ownerNo_fk_pet2 FOREIGN KEY (ownerNo) REFERENCES catOwner(ownerNo)
);
I'm trying to create a database for a project that works like a school with some teachers,courses,classes etc.
I need to create a new Table involving 2 tables however I'm getting an error when creating the table Classes_Teachers.
There are no primary or candidate keys in the referenced table 'Classes' that match the referencing column list in the foreign key 'FK__Classes_T__Class__11007AA7'.
Here is my SQL Code:
CREATE TABLE Teachers(
id INT,
name varchar(40),
email varchar(30) FOREIGN KEY REFERENCES Users(email),
PRIMARY KEY(id)
);
CREATE TABLE Courses(
name varchar(20),
acr varchar(4),
teacher int FOREIGN KEY REFERENCES Teachers(id),
PRIMARY KEY(acr)
);
CREATE TABLE Classes(
id varchar(2),
courses_acronym varchar(4) FOREIGN KEY REFERENCES Courses(acr),
year_Semesters varchar(5),
PRIMARY KEY(id,courses_acronym),
);
CREATE TABLE Classes_Teacher(
Classes_id varchar(2) FOREIGN KEY REFERENCES Classes(id),
Teachers_id INT FOREIGN KEY REFERENCES Teachers(id),
courses_acronym varchar(4) FOREIGN KEY REFERENCES Classes(courses_acronym),
PRIMARY KEY(Classes_id,courses_acronym)
);
The error comes from the foreign keys declared in table Classes_Teacher. To relate to the Classes table, you want to use both primary columns of the referred tables, instead of twn separated foreign keys.
Consider:
CREATE TABLE Classes_Teacher(
Classes_id varchar(2),
Teachers_id INT FOREIGN KEY REFERENCES Teachers(id),
courses_acronym varchar(4),
FOREIGN KEY (Classes_id, courses_acronym) REFERENCES Classes(id, courses_acronym),
PRIMARY KEY(Classes_id,courses_acronym)
);
Demo on DB Fiddle.
In table Classes you define a Primary Key on two columns. This is probably not needed if courses_acronym depends on ID.
CREATE TABLE Classes(
id varchar(2),
courses_acronym varchar(4) FOREIGN KEY REFERENCES Courses(acr),
year_Semesters varchar(5),
PRIMARY KEY(id),
);
In table Classes_Teacher you refer Classes twice. Shouldn't the second Foreign Key refer Courses?
CREATE TABLE Classes_Teacher(
Classes_id varchar(2) FOREIGN KEY REFERENCES Classes(id),
Teachers_id INT FOREIGN KEY REFERENCES Teachers(id),
courses_acronym varchar(4) FOREIGN KEY REFERENCES Courses(acr),
PRIMARY KEY(Classes_id,courses_acronym)
);
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),
);
Here's my problem when I write my SQLSever expressions:
There are no primary or candidate keys in the referenced table 'Room'
that match the referencing column list in the foreign key 'FK_Booking_RoomNo__4E298478'.
And some snapshots to my program:
CREATE TABLE Booking(
HotelNo NVARCHAR(4) not null,
GuestNo SMALLINT,
DateFrom DATETIME not null,
DateTo DATETIME,
RoomNo SMALLINT not null,
PRIMARY KEY (HotelNo,DateFrom,RoomNo),
FOREIGN KEY (HotelNo) REFERENCES Hotel(HotelNo),
FOREIGN KEY (GuestNo) REFERENCES Guest(GuestNo),
FOREIGN KEY (RoomNo) REFERENCES Room(RoomNo)); <---trouble on this line
CREATE TABLE Room(
RoomNo SMALLINT not null,
HotelNo NVARCHAR(4) not null,
RoomType NVARCHAR(25),
Price DECIMAL(5,2),
PRIMARY KEY (RoomNo,HotelNo),
CONSTRAINT fk_Room FOREIGN KEY (HotelNo) REFERENCES Hotel(HotelNo));
and here is the Hotel table
CREATE TABLE Hotel(
HotelNo NVARCHAR(4) not null,
HotelName NVARCHAR(25),
City NVARCHAR(25),
PRIMARY KEY (HotelNo) );
I tried to do some search on this problem, and it says this might be caused when there's no primary key defined in the table Room, but as above, it is defined.
Can someone please help me with this problem?
Thank you in advance.
Any reference to composite key must also include both columns.
FOREIGN KEY (RoomNo, HotelNo) REFERENCES Room(RoomNo, HotelNo))
Help please, I'm always getting this message:
There are no primary or candidate keys in the referenced table 'factIngresosCurso' that match the referencing column list in the foreign key 'fk_ingresos_curso'.
My tables:
create table factIngresos
(
cicCod char(6),
curcod char(5) references dimCurso,
cursec char(2),
codSec char(1) references dimSeccion,
tiempoid int references dimTiempo,
codHor int references dimHorario,
proCodUno char(5) references dimPersonal,
vacantes int,
inscritos int,
ingresoProyectado money,
ingresoNeto money,
becas money default 0,
constraint pk_Ingresos primary key(cicCod, curCod, curSec)
)
go
create table factIngCursoAlumno
(
alucod char(8) references dimAlumno,
cursec char(2), ciccod char(6), curcod char(5),
alucurCosto float, alucurefe float,
alucurPF float,
constraint pk_facIC primary key(alucod, cursec, ciccod, curcod),
constraint fk_ingresos_curso
foreign key(cursec, ciccod, curcod) references factIngresos(cursec, ciccod, curcod)
)
go
The primary key in factIngresos is
cicCod, curCod, curSec
Yet in your other table, you reference it using these columns and sequence:
foreign key(cursec, ciccod, curcod)
As you can see, just guessing from the names of the columns, the ordering is not the same as in the primary key specification.
You need to ensure that the column and their ordering (!!) is identical - so my guess is, you would need to use this foreign key configuration instead:
constraint fk_ingresos_curso
foreign key(ciccod, curcod, cursec) references factIngresos(ciccod, curcod, cursec)