Question

Differentiate between Hierarchical Database model and network database model.

Answer 1

Hierarchical data model	Network data model
Represents tree like structure with one root	Represents tree like structure with many roots
Reflects 1:N (one-to-many)relations	Reflects M:N(many to many) relations
There can be only one parent node	Allows a child to have more than one parent
Relationships between records is of parent-child type	Relationship is represented as pointers or links
There are multiple occurrence of child records and therefore inconsistency	This model is free from such inconsistency as there is only a single occurrence of a record set.
Searching a record is difficult as a child can be reached only through a parent	Searching a record is easy as there are multiple paths to a data element.

Answer 2

Hierarchical Database Model	Network Model
Network Model represents tree like structure with one root.	Network Model represents tree like structure with many roots.
Reflects 1:N (One to many) relationship	Reflects M:N (Many to many) relationship
There can be only one node at the parent level	It allows a record to have more than one parent.
Example:	Example :
Relationship between records is of parent child type	Relationship between records is expressed in the form of pointers or links(Graphs).
Searching for a record is very difficult since one can retrieve a child only after going through its parent record.	Searching a record is easy since there are multiple access paths to a data element
There are multiple occurrences of child records, which lead to problem of inconsistency during the update operations	This model is free from update anomalies because there is only a single occurrence for each record set.
Record relationship implementation is simple due to the use of pointers	Record relationship implementation is complex due to the use of pointers