辅导schema留学生、讲解R设计、辅导R编程语言、讲解BCNF
讲解留学生Prolog|辅导留学生 Statistics统计、回归、迭代
Exercise 1
Consider a relation with schema R (A, B, C, D) and FDs the set F:
F= {AB→C C→D D→A }
a.(10%) Find all the candidate keys of R.
b.(5%) Indicate all BCNF violations for R.
c.(10%) Decompose the relations into collections of relations that are in BCNF.
d.(5%) Indicate which dependencies, if any, are not preserved by the BCNF decomposition.
Exercise 2
Consider a relation with schema R (A, B, C, D) and FDs the set F:
F ={ A→B
A→C
C→D }
a.(5%) Determine the set of all candidate keys for the relation schema.
b.(5%) Determine the highest normal form (no NF, 1NF, 2NF, 3NF, BCNF) that the relation schema is in. Explain your answer.
c.(10%) Decompose the relation schema into new relation schemas that satisfy the next higher normal form.
d.(10%) Show the minimal covers of functional dependencies for the decomposed relation schemas.
e.(10%) List the candidate keys of the decomposed relation schemas.
f.(10%) Prove that the decomposition is a lossless join decomposition and/or dependency preserving.