Hi, This is relational databases question I\'m struggling with this homework que

Question

Hi,

This is relational databases question

I'm struggling with this homework question. Trying to better understand what's being asked. Could you please explain your answer. Many thanks

Consider the relation schema TEACH Course, Professor, Time, Room, Student, Grade with the following set of Functional Dependencies (FDs) Course -> Professor Time, Room} -> Course Time, Professor)- Room Time, Student)Room Student, Course Grade 3.1 What are the prime attributes of TEACH? Justify your answer (i.e., show the main steps and your working (0.5 Mark) used for computing the prime attributes) 3.2 Justify whether TEACH is in BCNF with respect to . If TEACH is not in BCNF with respect to identify a BCNF decomposition for TEACH (you need to show the main steps used for identifying this BCNF decomposition) and justify whether this BCNF decomposition is dependency preserving.1.5 Mark)

Explanation / Answer

{time,student}+ --> {time,student,room}

                            -->{time,student,room,course}

                            -->{time,student,room,course,Professor,grade}

So, {time,student} is a super key.

As it is a minimal super key, then we can call it candidate key.

Now,we can see that they are not in BCNF:

1. Course --> Professor   // violates BCNF since it is non-trivial and the lefthand side is not a key

2.{Time,Room} --> Course // violates BCNF since it is non-trivial and the lefthand side is not a key and it is also a transitive FD because {Time,Room} --> Professor

3.{Time,Student} --> Room // It is in BCNF as the left side is a key

4.{Student, Course} --> Grade //violates BCNF since it is non-trivial and the lefthand side is not a key

Decomposition into BCNF:

Cp{Course, Professor}

Left items :: { Course, Time, Room, student, Grade }

Trc{ Time, Room, Course }

Left items :: { Time, Room, student, Grade }

ts{ Time,student}

scg{Sudent,Course, Grade}

tpr{Time,professor,room}

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.