Answer the following: --> If X and Y are subsets of attributes of relation R, th
ID: 3739669 • Letter: A
Question
Answer the following:
--> If X and Y are subsets of attributes of relation R, then we say that set Y is functionally dependent
on set X if:
for each X value there is only one Y value
for each Y value there is only one X value
no two X values have the same Y value
when two rows have the same Y value they also have the same X value
--> Which of the following is not one of the major objectives of normalization?
removing redundancy
improving eciency
removing anomalies
increasing model exibility
--> A constraint between two or more attributes in which a nonkey attribute is determined by a portion
of the key is called a
partial functional dependency
partial attribute dependency
transitive dependency
partial transitive dependency
Explanation / Answer
DEFINATION : Functional dependency is a relationship that exists when one attribute uniquely determines another attribute. If R is a relation with attributes X and Y, a functional dependency between the attributes is represented as X->Y, which specifies Y is functionally dependent on X. The attributes of a table is said to be dependent on each other when an attribute of a table uniquely identifies another attribute of the same table.
1.improving model flexbiliy.we can safely assume that all other objectives are more important than this.
2.partial functional dependency.