Definition of Hierarchical Database

Database management systems manage large amounts of data.

In software engineering, you have many different ways to store data. One of the lesser used data models is the hierarchical database, which stores data in a series of simple parent/child relationships. The hierarchical database is easy to understand; it can be limited compared to other database structures, such as relational databases.

Databases

Databases and database management systems are used in a wide variety of applications. Any software that uses a large amount of data most likely uses some sort of database. Databases are the organized collections of data in a specified format, which is controlled by a database management system.

Hierarchical Databases

Hierarchical databases store data in a series of linked parent/child relationships. Each entry in a database can have a single parent entry, and one or more child entries. For instance, an entry for "Ferrari" may have the entry "Automobile Manufacturers" as a parent, and several child entries for different models of car made by Ferrari.

Tree Structure

Hierarchical databases are in actuality what is known as a tree. Trees are data structures commonly used in software engineering to model data. Each tree is made up of "nodes." Each node represents some sort of value or data object. Each node can have one parent node, and one or more child nodes, creating a series of branching pathways. This is known as a "one-to-many relationship."

Hierarchical Databases vs. Relational Databases

Relational databases are much more commonly used than hierarchical databases. This is in part because hierarchical structures can be modeled within a relational database, and because relational database are much less limited in their design. Relational databases allow relational links to be created between entries without the limitation of a single parent as in hierarchical databases. This allows for much more complex organizations of data. However, the connections can still be restricted in a relational database to form a tree-like structure, as in a hierarchical database.

References

• UnixSpace.com: Database Models