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Hierarchical database model

Hierarchical database model is a structure of data organized in a tree-like model using parent/child like relationships, therefore there won't be too many relationships. In a hierarchical database, an entity type can be either a parent or a child; under each individual entity is is more multiple entities. Entity types are related to each other using tree mapping, which is represented by one parent with many child relationships. There are also attributes of a specific data recorded under an entity. 

A tree structure is a way of representing the hierarchy of a structure in a model to display which entity is derive from either a parent or a child. The Hierarchical database looks like a tree structure because its data is a representation of a tree, which the model is downward where the leaves sprouts from branches. The leaves are the child and the branches are the parents. Both child and parent are data represented as entity within the hierarchy model. Each is recorded and connected, therefore this database will looks like a tree like structure.

The tree like structure can be repeated data, usually with many children under single parent information. Data is a series of records, which have a set of values within it. All of the collected data is recorded in each type. These types are equal to the tables in other database model, and each parent or child is the equivalent of a row or column in a database table. In a hierarchical model, Parent/Child relationships are all link together by certain types of data in a category. The links are mapped in the relationships so it would look like a tree structure with many branches sprouting form many branches. For example, a company will store information about an employee. So in the beginning of the tree will be the employee name. Below the name will be the data of the employee’s number, department, salary, etc. Information such as birthday, children, and age will be stored also.

Therefore the data of the employee will form a hierarchy structure, where the employee information is represented by a segment and the child segment which then becomes their own parent segment to others child segments. For example if an employee has 3 cars, then there would be 3 child data under the one parent employee segment. And each of the 3 cars has child segments, like make or model. So in a hierarchical datable the parent-child relationships are many.


Hierarchical database manage systems links together information of records together. Each parent is a owner of many children, and each children will be parent themselves therefore the children will have many children. Hierarchical is use in management systems to determine the ranking of employees, or departments. For example, take the corporate structure of a company. On the top is the Stockholders which is the most important parent, then comes the Board of Directors, then the CEO, under the CEO manages the CFO, COO, CIO and etc.

Wikipedia Link - http://en.wikipedia.org/wiki/Hierarchical_model