Time remaining:
Database question, Is this still bcnf?

Computer Science
Tutor: None Selected Time limit: 0 Hours

I created user registration and log in screen. If same email user and same user can be taken over and over, isn't it violate bcnf rule?

Aug 13th, 2014

Pragmatically, You are correct that when you declare something as a primary key, that it must correspond to one tuple. Databases will not allow you to store a tuple in a table if the primary key already exists for a tuple in the table.

Theoretically, If R is a relation with the following set A of attributes {a1,a2,...,an}, then a primary key on the relation R would be a subset P⊂A such that for F:P→A, we have ∀x,y∈P F(x)=F(y)→x=y. This basically just means that the primary key forms a one-to-one mapping from the domain of keys to the range of corresponding tuples.

If you have that two tuples are the same A and B, then this implies that A=B,and we still have that F(A)=F(B) so that there is no violation, in that sense.


Aug 13th, 2014

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.
Click to visit
The Notebank
...
Aug 13th, 2014
...
Aug 13th, 2014
Feb 19th, 2017
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer