Data Integrity and Normalization - Short Questions

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.

 

ics part 2 computer data integrity and normalization short questions


Chapter No.4: 
Data Integrity & Normalization
Short 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.



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