Hierarchical Data Model Vs Network Data Model Vs Relational Data Model

Hierarchical Data Mode	Network Data Model	Relational Data Model
Relationship between records is of parent-child type.	Relationship between records is expressed in the form of pointers or links.	A relation that contains a key for each record involved in the relationship represents relationship between records.
Many to many relationships cannot be expressed in this model.	Many to many relationships can be implemented.	Many to many relationships can be easily implemented.
It is a simple, straightforward and natural method of implementing record relationships.	Record relationship implementation is quite complex due to the use of pointers.	Relationship implementation is very easy through the use of a key or composite key field.
This type of model is useful only when there is some hierarchical character in the database.	Network model is useful for representing such records, which have many to many relationships.	Relational model is useful for representing most of the real-world objects and relationships among them.
In order to represent links among records, pointers are used. Thus, relations among records are physical.	In order to represent links among records, pointers are used. Thus, relations among records are physical.	Relational model does not maintain physical connection among records. Data is organized logically in the form of rows and columns and stored in the table.
Searching for a record is very difficult since one can retrieve a child only after going through its parent record.	Searching for a record is easy since there are multiple access paths to a data element.	A unique, indexed key field is used to search for a data element.
During updating or deletion process, chances of data inconsistency is involved.	No problem of inconsistency exists in network model because a data element is physically located at just one place.	Data integrity maintaining methods like normalization process, etc. are adopted for consistency.