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WorksheetsUNIT IV Normalization
Total questions: 20
Worksheet time: 11mins
Normalisation is:
Removing all necessary data from a database
Organising a database to remove repeated entries and increase the accuracy of the data
Putting fields from different tables into one big database
What is an atomic field?
A field that contains multiple items of data
A field that is repeated
A field that contains only one item of data
What is a foreign key?
A unique identifier in a database
A primary key of one table that appears in another table
A field that should not be in a table and needs removing
A table in ____ contains no transitive dependencies.
1NF
2NF
3NF
none of the above
When is a table is said to be 3NF
Normalization improves performance by reducing redundancy.
If and only if it is in 2NF and every non key attribute is Non-transitively dependent on the primary key
It involves introduction of redundancy in data
None of the above
Identify the types of Data Anomalies:
Add, Delete and Save anomalies
Insert, Add and Save anomalies
Update, Save and Insert anomalies
Insert, Delete and Update anomalies
Which is the best example of a Primary Key?
Price
Name
Address
IC No
Consider the relation scheme R = {E, F, G, H, I, J, K, L, M, N} and the set of functional dependencies {{E, F} -> {G}, {F} -> {I, J}, {E, H} -> {K, L}, K -> {M}, L -> {N} on R. What is the key for R?
{E, F}
{E}
{E, F, H}
{E, F, H, K, L}
Relation R has eight attributes ABCDEFGH. F = {CH -> G, A -> BC, B -> CFH, E -> A, F -> EG} is a set of functional dependencies (FDs) so that F+ is exactly the set of FDs that hold for R. How many candidate keys does the relation R have?
5
3
4
6
In a schema with attributes A, B, C, D and E following set of functional dependencies are given
{A -> B, A -> C, CD -> E, B -> D, E -> A}
Which of the following functional dependencies is NOT implied by the above set? (Hint: use inference rules, Reflexive, Augmentations, Transitive)
CD -> AC
BC -> CD
AC -> BC
BD -> CD
Expand PJNF
(a)
1.Which one of the following is a wrong informal design guidelines for relational schema?
Semantics of the Attributes
Reducing the Redundant Value in Tuples
Reducing Null values in Tuples
Allowing spurious Tuples.
--------is a set of constraints between two attributes or two sets of attributes in a relation.
(a)
If A->B holds and Y is attribute set, then AY->BY also holds. Name this rule
(a)
if A->B holds and B->C holds,
then A->C also holds.Name this rule
(a)
Which among the following is not a secondary rule.
union
difference
composition
decomposition
• If there are more than one attributes in primary key and ‘A’ be a non prime key attribute. If ‘A’ is not dependent upon all prime key attributes then ------exists.
(a)
In any relation R, if for a particular value of X, Y has more than one value.Name this functional dependency
(a)
In any relation R, X -> Y is ------------ if Y is a subset of X.
(a)
A relation is in second normal form if it is in 1NF and all non primary key attributes must be (a) dependent upon primary key attributes
