954 views
0 votes
0 votes

I've some elementary doubts regarding Foreign keys (referential integrity) :

  • Can a foreign key consist of a collection of attributes - ie. can two or more columns collectively form a foreign key?
  • If foreign key refers to a column within the same table, then is it compulsory that the referred column must be UNIQUE constrained?
  • Can the Primary key of a column be a foreign key referring to some other relation?

 

Doubt related to Third Normal Form:

Is it true that 3NF is inadequate for a relation that has either:

  • Multiple candidate keys
  • Composite candidate keys
  • Overlapping candidate keys

If possible, please provide an example.

Thank You.!

Please log in or register to answer this question.

Related questions

0 votes
0 votes
2 answers
2
0 votes
0 votes
3 answers
3
5 votes
5 votes
3 answers
4
GateAspirant999 asked Oct 29, 2016
2,342 views
A relation R(A,B,C,D,E,F) holds following FDs$AB\rightarrow C$$C\rightarrow D$$D\rightarrow EA$$E\rightarrow F$$F\rightarrow B$The number of minimal candidate keys of R a...