Functional Dependencies
FD properties
- For this discussion, we focus on the columns of one relation.
- X, Y etc. are sets of columns.
- Xi, Yi etc. are individual columns.
Proofs of these properties are mostly easy — not discussed
here, consult textbook.
FDs are transitive
If
X → Y
and
Y → Z
then
X → Z
In the
BadAlbum
table:
artist, title → label
label → label_website
which implies:
(artist, title) → label_website
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