I am working on a textbook question and it asks the following:
Let R(A,B,C,D,E) be decomposed into relations with the following three sets of attributes:
{A,B,C} , {B,C,D}, {A,C,E}
For each of the following sets of functional dependencies, determine if the dependencies
are preserved by the decomposition.
**Functional Dependencies:**
AC -> E and BC -> D
I am not sure how to solve this, and the textbook doesn't provide a clear enough explanation on dependency preserving. Can someone please explain how to do this? Thank you in advance.
R = {A,B,C,D,E} decomposed into R 1 ={A,B,C} , R 2 ={B,C,D} and R 3 ={A,C,E}.
"determine if the dependencies are preserved by the decomposition."
Yes they are as BC->D is preserved in R 2 and AC->E is preserved in R 3 as is very apparent!
Note - Although a decomposition may be dependency-preserving it is not necessary that it is in a higher normal form.
There is an easy method to check whether a decomposition is dependency-preserving. Check this video.
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