Boyce-Codd Normal Form (BCNF)
Reln R with FDs F is in BCNF if, for all X A in
- A X (called a trivial FD), or
- X is a superkey
3NF plus: no prime field describes a non-prime field
Example: R = (branch, cust, banker)
- FDs: banker ? branch and cust, branch ? banker
- Is R in 3NF? BCNF?
Problems:
- Bankers must have at least one customer
- Branch stored redundantly for each of a banker’s customers