CODEWITHSUNDEEP
mysqlforeign-keyscomposite-primary-key
DJPharaohCHS
DJPharaohCHS

Reputation: 301

Can a Foreign Key be part of a Composite Primary Key for another table?

I have two(of many) tables in a music database:

Concerts: ArtistID,ConcertID,ConcetName,VenueID ConcertDetails: ConcertDate, ConcertID, Cost

The ConcertDetails tables as you see, uses ConcertID which is also in the Concerts table. I combine ConcertDate & ConcertID to make a Composite Primary Key for ConcertDetails. However since this relates to ConcertID from Concerts table it also needs to be a Foreign Key. Is this ok to do?

Upvotes: 12

Views: 12514

Answers (1)

Bill Karwin
Bill Karwin

Reputation: 562328

Yes, of course. It's common for a subset of a primary key to be a foreign key. Any many-to-many table does this for instance. In your case:

CREATE TABLE ConcertDetails (
  ConcertDate DATE NOT NULL,
  ConcertID INT NOT NULL,
  PRIMARY KEY (ConcertDate, ConcertID),
  FOREIGN KEY (ConcertID) REFERENCES Concerts(ConcertID)
);

Upvotes: 18

Related Questions