Comparison among Hierarchical Model, Network Model and Relational Model:

Data structure:

Hierarchical Model:

• A) It is one to one or one to many relationship.

• B) It is based on parent child relationship.

Network model:

• A) It follows the many to many relationship.

• B) A record can many have parent as well as many children.

Relational model:

• A) one to one. one to many , and many to many relationship.

• B) based on relation data structure

Data manipulation :

Hierarchical model:

• A) Not any independent stand alone query interface.

• B) Retrieve algorithms are complex and asymmetric.

Network data model:

• A) codasyl(conference on data system language)

• B) retrieve algorithms are complex and symmetric

Relational data model:

• A) Relational data model are what bring many sources into common query (such as sql)

• B) Retrieve algorithms are simple and symmetric.

Data integrity:

Hierarchical Data Model:

• A) cannot insert any information of a child who does not have any parent.

• B) multiple occurrence of child record with lead to problems of inconsistency during the update operation.

• C) deletion of parent results in deletion of child record.

Network model

• A) does not suffer any insertion anomaly

• B) it is free from update anomalies

• C) edit free delete anomalies

Relational model

• A) does not suffer any insert anomaly

• B) free from update anomalies because of normalization process.

• C) free from delete anomalies.

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