CSCI 4333 Database Design and Implementation – Exercise (4) Xiang Lian The University of Texas Rio Grande Valley Edinburg, TX 78539 xiang.lian@utrgv.edu

Attribute Closure and Entailment If X = {AB} and F = {AD, BCEJ, BDAE, EJG, ADEH, HDJ}, what is XF+? Are the FDs ABC and AEG entailed by F?

Derivation with Armstrong's Axioms Using only Armstrong's axioms and the FDs (a) ABC (b) ABE (c) CD Give a complete derivation of the FD AD.

BCNF R={B, C, E} F={EB, BCE} What are candidate keys in R? Is R in BCNF? If not, how to decompose R losslessly? BC, EC

3NF Given R= {BCDFGH} with a set of FDs F={BGCD, GF, CDGH, CFG, FD} Use the 3NF algorithm to obtain a lossless, dependency-preserving decomposition into 3NF.