In a hierarchical database, records contain groups of parent/child relationships, similar to a tree structure. In a hierarchical database, every record is either at the top of a hierarchy (a root record) or is the child of another record in the hierarchical database. An example of hierarchical data could be displaying the hierarchy of departmental responsibility or 'who reports to whom'. In an XML-like database, the tables are hierarchical. In Relational Database model, an example of hierarchical data could be displaying the hierarchy of departmental responsibility or 'who reports to whom'. The bibliographic database Cancerlit uses a hierarchical database. Lotus Notes is the most popular hierarchical database managment system in use today.
Many companies and other organizations support their operations by maintaining two databases, a hierarchical database and a relational one.
2). Relational Databases:
The most popular databases today are Relational Database Management Systems (RDBMS). There is good reason for this. They are easy to use and are normally efficient. However, object database servers may someday overtake the relational database servers.
Examples of these kinds of database applications are accounts payable, accounts receivable, order processing, and inventory control. Because these types of applications contain relatively simple data relationships and schema design, relational database management systems (RDBMs) are better suited for these applications.
2) OO databases:
Information analysis applications focus on providing the capability to navigate through and analyze large volumes of data. Examples of these applications are CAD/CAM/CAE, production planning, network planning, and financial engineering. These types of applications are very dynamic and their database schemas are very complex. This type of application requires a tightly-coupled language interface and the ability to handle the creation and evolution of schema of arbitrary complexity without a lot of programmer intervention.
Object-oriented databases support these features to a great degree and are therefore better suited for the information analysis type of applications. Object database servers use an Object Query Language (OQL) as a standard language for communication. OODBs are also used in applications handling BLOBs (binary large objects) such as images, sound, video, and unformatted text. OODBs support diverse data types rather than only the simple tables, columns and rows of relational databases.
Northwest Natural Gas uses an OODB for a customer information system. Ameritech Advanced Data Services uses an OODB for a comprehensive management information system that currently includes accounting, order entry, pricing, and pre-sales support.
No comments:
Post a Comment