Boyce-codd normal form (BCNF)


  • Boyce-Codd normal form (BCNF) was proposed as a simpler form of 3NF, but it was found to be stricter than 3NF.
  • That is, every relation in BCNF is also in 3NF; however, a relation in 3NF is not necessarily in BCNF.
  • 3NF, which eliminates most of the anomalies known in databases today, is the most common standard for normalization in commercial databases and CASE tools.
  • The few remaining anomalies can be eliminated by the Boyce-Codd normal form (BCNF). BCNF is considered to be a strong variation of 3NF.
  • BCNF is a stronger form of normalization than 3NF because it eliminates the second condition for 3NF, which allowed the right side of the FD to be a prime attribute.
  • Thus, every left side of an FD in a table must be a superkey. Every table that is BCNF is also 3NF, 2NF, and 1NF, by the previous definitions.
  • Boyce-Codd Normal Form (BCNF) is one of the forms of database normalization.
  • A database table is in BCNF if and only if there are no non-trivial functional dependencies of attributes on anything other than a superset of a candidate key.
  • BCNF is the advance version of 3NF. It is stricter than 3NF.
  • A table is in BCNF if every functional dependency X → Y, X is the super key of the table.
  • For BCNF, the table should be in 3NF, and for every FD, LHS is super key