Re: PLEASE HELP !!

>>I didn't ask for anyone to do my homework.<<

Oh yes you did...when you asked about anything above BCNF (Boyce/Codd normal form which is the proper replacement of the old 3NF...just in case you were wondering :-)

For BNF4 and BNF5...check out Chapter 11 in An Introduction to Database Systems by C.J. Date (My current copy is the sixth edition)

The definition of the fourth normal form makes use of a new kind of dependency, called a multivalued dependency,(MVD) which are a generalization of functional dependences.

Definition:
Multivalued dependence: Let R be a relation and let A, B, and C be arbitrary subsets of the set of the attributes or R. Then we say that B is multidependent on A if and only if the set of B-values matching a given(A-value,C-value) pair in R depends only on the A-value and is independent of the C-value.

Definition:
Fourth normal form(so-called because at the time BCNF was still usually called the third normal form): relation R is in 4NF if and only if, whenever there exist subsets A and B or the attributes of R such that the (nontrivial) MVD A-->>B is satisfied, then all the attributes of R are also functionally dependent on A.

>>Nor did i ever mention wanting to work in any place doing anything as boring
as database management. It's a unit I think is useful, but not something I would like to do for a living

The purpose of my original post was to see if there was anyone out there who could help me gain a few marks by getting an advantage over other students by obtaining rare resources.
<<
NAAA....there is no one here but BORING database management types :-)

Now that you have the above are you going to discuss the work of Fagin and Heath???

>>Get a life.<<

Sorry I already have one :-)
Paul in VT Received on Mon Apr 24 2000 - 00:00:00 CDT