Normal Forms

Question 1

key

Answer 1

If K is a key in r, k functionally determines all attributes in r

Question 2

Cover

Answer 2

• F covers G iff the closure of G is a subset of the closure of f
• every FD in G can be inferred from F

Question 3

Equality

Answer 3

Closure of F = Closure of G

Question 4

Minimal Set

Answer 4

• Use IR 4 (X->YZ is X->Y and X->Z)
• No extraneous attributes on left hand side
• No FD’s that can be inferred

Question 5

Minimal Cover

Answer 5

Minimal set of FD’s that is equivalent to F

Question 6

Superkey

Answer 6

A set of attributes S subset-of R such that no 2 tuples t1 and t2 in any legal relation state r in R, will have t1[S] = t2[S].

Question 7

Key

Answer 7

Superkey but if u remove any attribute it will no longer be a super key (minimal Superkey).

Question 8

candidate key

Answer 8

If a relation schema has more than one key each is called a candidate key

Question 9

primary and secondary keys

Answer 9

Candidate key is arbitrarily designated to be a primary key and then secondary keys are the remaining.

Question 10

Prime Attribute/non-prime attribute

Answer 10

• member of some candidate key

- not a member of any candidate key

Question 11

1NF

Answer 11

All attributes depend on the key

• no composite, and multivalued attributes and no nested relations

Question 12

2NF

Answer 12

is already in 1NF

Every non-prime attribute is fully dependent on every key

Question 13

3NF

Answer 13

every non prime in R is

• already in 2NF
• not transitively dependent on every key in R

Question 14

BCNF

Answer 14

whenever an FD X->A holds in R, X is a superkey

implies already in 3NF

Question 15

loseless preservation property/non-additive join

Answer 15

asfdasdf

Question 16

dependency preservation property

Answer 16

asdfs