-
relational data
model a
superkey is any set of
attributes that
uniquely identifies each
tuple of a relation.
Because superkey values are unique, tuples...
-
duplicate combinations of values. A
candidate key is a
minimal superkey, i.e., a
superkey that doesn't
contain a
smaller one. Therefore, a
relation can...
-
Superkey A
superkey is a set of
column headers for
which the
values of
those columns concatenated are
unique across all rows. Formally: A
superkey is...
- ID,
Supplier ID}}. No
component of that join
dependency is a
superkey (the sole
superkey being the
entire heading), so the
table does not
satisfy the...
-
subset of X,
meaning X → Y is a
trivial functional dependency), X is a
superkey,
every element of Y \ X, the set
difference between Y and X, is a prime...
- be
considered as the table's
superkeys. However, only S1, S2, S3 and S4 are
candidate keys (that is,
minimal superkeys for that relation)
because e.g...
-
multivalued dependencies X ↠ {\displaystyle \twoheadrightarrow } Y, {X, Y} is a
superkey—that is, the
combination of all
attributes in X and Y is
either a candidate...
-
primary key is a choice[clarification needed] of a
candidate key (a
minimal superkey); any
other candidate key is an
alternate key. In
relational database terms...
-
implied by the
candidate key(s) of R if and only if each of A, B, …, Z is a
superkey for R. The
fifth normal form was
first described by
Ronald ****in in his...
- ON
UPDATE CASCADE ON
DELETE RESTRICT )
Candidate key
Compound key
Superkey Junction table Coronel,
Carlos (2010).
Database Systems: Design, Implementation...
