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mnava18
Posts: 86
Posted 23:10 Apr 16, 2016 |

im having trouble seeing why {course,quarter,section_number}--->{faculty} is a FD.(Im getting this from your video lecture ) i think after i get this down , ill be good lol. the course column is confusing me the most on this table.  i dont see any other column that matches it. so i dont see how quarter and section# do.  course has cs422 and cs 520 and quarter for those 2 courses is fall and fall. you cannot have fall and fall mapping to 2 different courses(from what i understand). so how does {course,quarter,section_number}--->{faculty} become a FD? unless i heard wrong in the video lecture (which has horrible sound lol , so possible)

 

the only way  i can see this happening is like this,  Course-->quarter is not a FD ,   quarter -->course  is a FD. is this enough to be able to use course in the  {course,quarter,section_number}--->{faculty} FD?

 

Last edited by mnava18 at 04:18 Apr 17, 2016.
ajoshi6
Posts: 46
Posted 09:10 Apr 17, 2016 |

{course,quarter,section_number}--->{faculty} individually taking in account this FD then you can take it as {faculty}-->{course},{section_number}, faculty cannot determine quarter because C.Sun is for Fall2013 and E.Kang is also for Fall2013 so it is not FD.

same with quarter-->course.

but course--> quarter is possible

 

thanks

cysun
Posts: 2935
Posted 09:25 Apr 17, 2016 |

The {course, quarter, section_number} combination determines a class, e.g. CS422 Section 1 in Spring 2016, and each class only has one instructor.

Don't try to make up your own terminology like "mapping". Read the FD definition in the lecture notes.

And no, {course}->{quarter} is not a FD.