text: Q:
  
  A short summary of what BCNF is?
  
  For my exam I am revising for in January I will need to know all about Boyce-Codd Normal Form and possibly have to write a short summary about what it is. 
  In a paragraph or so, what exactly is BCNF as I have looked on many sites and the descriptions are quite complex so it's not easy to get my head around. Thank you for any help.
  
  A:
  
  Boyce–Codd Normal Form (BCNF)
  A relation R(X) is in Boyce–Codd Normal
  Form if for every non-trivial functional
  dependency Y → Z defined on it, Y contains
  a key K of R(X).
  That is, Y is a superkey for
  R(X).
  Example: Person1(SI#, Name, Address)
       The only FD is SI# → Name, Address
  
  Since SI# is a key, Person1 is in BCNF
  Anomalies and redundancies, as discussed
  earlier, do not occur in databases with
  relations in BCNF.
  Non-BCNF examples:
  Person(SI#,Name,Address,Hobby)
  The FD SI# → Name,Address does not satisfy
  conditions for BCNF since the key is
  {SSN,Hobby}
  HasAccount(AcctNum,ClientId,OfficeId)
  
  The FD AcctNum → OfficeId does not satisfy
  BCNF conditions if we assume that keys for
  HasAccount are {ClientId,OfficeId} and
  {AcctNum,ClientId}, rather than AcctNum.
  
  You can refer to below link for detailed explanation.
  http://www.cdf.toronto.edu/~csc343h/fall/08/lectures/wk12/wk12_BCNF2-up.pdf
  Hope it helps..
  
  