Data Integrity and
Normalization - Short Questions. Find
the most important and more conceptual short questions with answers of Computer
Chapter No.4: Data Integrity and Normalization, ICS Part 2 | 2nd Year, on the
database management system (DBMS) normalization (1NF, 2nd NF, and 3rd NF) for
the interview and final examinations for all boards of Pakistan.
Chapter No.4: Data Integrity & NormalizationShort Questions & Answers
Q.1: What is database integrity?
Answer:
Database integrity refers to the correctness and consistency of
data. it is another form of database protection. It is concerned with the quality
of the data itself. Is usually expressed in terms of certain constraints which are
the consistency rules that the database is not permitted to violate.
Q.2: Differentiate between entity integrity and referential integrity?
Answer:
Entity Integrity: Entity Integrity is a constraint on
primary values that state that no attribute of a primary key should contain
nulls.
Referential Integrity: Referential Integrity is a
constraint on foreign key values that states that if a foreign key exists in a
relation, then either the foreign key value must match the primary key value of
some tuple in its home relation or the foreign key value must be completely null.
Q.3: What is normalization?
Answer:
Normalization is the process of analyzing the dependencies of
attributes within entities. Attributes for each entity are checked
consecutively against three sets of rules, making adjustments when necessary to
put the entity in First, Second, and Third normal form. It is based on the analysis
of functional dependence.
Q.4: What is a functional dependency?
Answer:
A functional dependency is a particular relationship between two
attributes. For any relation R, attribute B is functionally dependent
on attribute A if, for every valid instance of A, that value of A
uniquely determines the value of B. The functional dependence of B
on A is represented by an arrow.
Example:
A `\rightarrow` B
Q.5: What is a synonym?
Answer:
A synonym is created when two different names are used for the
same information. If an attribute resides in more than one entity, make sure
that all entities use the same attribute name.
Q.6: What is a homonym?
Answer:
In a database, a homonym is created when the same name is used for tow
different attributes.
Q.7: What is redundant information?
Answer:
A redundancy occurs when the same information is stored in multiple
files or two different ways.
Q.8: What is mutually exclusive data?
Answer:
Mutually exclusive data exists when attributes occur whose values
can be expressed as “yes/no” indicators, can not all be true or any single entity.
Q.9: What is the 1st Normal Form?
Answer:
A relation R is in 1st Normal Form if and
only if all underlying domains contain atomic values only. A relation R
has always a primary key associated with it.
Q.10: What is the 2nd Normal Form?
Answer:
A relation is in 2nd Normal Form if it is in 1st
NF and every non-key attribute is full functionally dependent on the primary
key (key attribute).
Q.11: What is the 3rd Normal Form?
Answer:
A relation is in 3rd Normal Form if it is in 2nd
NF and no transitive dependencies exist.
Q.12: What is a transitive dependency?
Answer:
It is a functional dependency in a relation between two (or more)
non-key attributes. A non-key attribute must not depend on any other non-key
attribute.
Q.13: What is a partial functional dependency?
Answer:
A partial functional dependency exists if one or more non-key
attributes are functionally dependent on part of the primary key.
Q.14: What is atomic value?
Answer:
An atomic value is a value that can not be further sub-divided or
decomposed.
Q.15: What is a database anomaly?
Answer:
Database anomaly is the problem/flaw in the database which
occurs because of poor planning and storing everything in a flat database. Generally, it is removed by the process of normalization
which is performed by dividing/joining the tables.
Three Types of Anomalies:
Insertion Anomaly: It occurs when you insert inconsistent
information into a table.
Deletion Anomaly: It occurs when you delete a record that may contain attributes that shouldn't be
deleted.
Update / Modification Anomaly: It is a data inconsistency
that results from data redundancy and a partial update.
➤ Data Integrity & Normalization - MCQs
➤ Table and Query
➤ Database Design Process
➤ Basic Concepts & Terminology of Databases
➤ Data Basics
➤ Getting Started with C
➤ Elements of C
➤ Input/Output
➤ Decision Constructs
➤ Loop Constructs
➤ Functions in C
➤ File Handling
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