# 查看完整版本 : Database Administration COMP7640 Assignment 2 Question 3 請教

## Database Administration COMP7640 Assignment 2 Question 3 請教

[font=arial, sans-serif][size=4][color=#222222]Consider the attribute set R = ABCDEG and the FD set[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222][/color][/size][/font][font=arial, sans-serif][size=4][color=#222222]F = {AB → C, AC → B, E → BD, B → D, BC → A,C → G}[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222][/color][/size][/font][font=arial, sans-serif][size=4][color=#222222]1. Find all the candidate keys for R.[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222][/color][/size][/font][font=arial, sans-serif][size=4][color=#222222]2. Consider R1 = ABCD resulting from a decomposition of R. [/color][/size][/font][font=arial, sans-serif][size=4][color=#222222](1) Write down a minimal cover for F projected on R1.[font=arial, sans-serif][size=4][color=#222222](2) Is R1 in BCNF? Justify your answer.[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222][/color][/size][/font][font=arial, sans-serif][size=4][color=#222222]3. Which of the following decompositions of R = ABCDEG, with the same set of[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222]dependencies F, is (a) dependency-preserving? (b) lossless-join?[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222][/color][/size][/font][font=arial, sans-serif][size=4][color=#222222](a) {ACDE, BEG}[/color][/size][/font][font=arial, sans-serif][size=4][color=#222222](b) {ABCE, BD,CG}[/color][/size][/font]

betheny 2014-11-16 10:45 PM

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