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jonathankroening
Posts: 39
Posted 16:41 Oct 09, 2013 |

[Paraphrased from the textbook] --> FDs are constraints, so you can't get at them by looking at the current contents of the table. You discover them by considering the rules governing the contents of the table.

There are a couple of rules I'm not sure if we should consider but seem to be implied by the table:

1.  Each professor is always assigned the same section_number whenever teaching the same course (no matter which quarter)

2.  Each course can only be taught by one professor (ex. CS520 is only taught by C. Sun albeit in 2 different quarters)

What do you all think?

cydneyauman
Posts: 12
Posted 16:47 Oct 09, 2013 |

1.  I assumed that a professor is assigned a course and section number each quarter.  And that even though the table only ever had (1) section - I assumed there could be additional sections.

 

2. For me - this relates back to my assumptions above.

cysun
Posts: 2935
Posted 16:58 Oct 09, 2013 |
jonathankroening wrote:

[Paraphrased from the textbook] --> FDs are constraints, so you can't get at them by looking at the current contents of the table. You discover them by considering the rules governing the contents of the table.

There are a couple of rules I'm not sure if we should consider but seem to be implied by the table:

1.  Each professor is always assigned the same section_number whenever teaching the same course (no matter which quarter)

2.  Each course can only be taught by one professor (ex. CS520 is only taught by C. Sun albeit in 2 different quarters)

What do you all think?

1. Not true, as explained by cydneyauman.

2. Not true either, e,g. CS201 is has been taught by many different professors.