Introduction to RDBMS, OODBMS and ORDBMS
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Thanks to the Internet, the legal need to keep track of lots of business information, new marketing methods, and the explosion of data-intensive scientific progress, databases are being used more than ever before for storing and accessing information. There are currently three different models in use for database management systems: relational, object-oriented, and object-relational. This article introduces all three, and discusses their relative strengths and weaknesses.
Relational Database Management System
Edgar F. Codd at IBM invented the relational database in 1970. Referred to as RDBMS, the relational model extended two previous database systems, the hierarchical and the network models. After Codd’s development, “prototype RDBMS were developed at IBM and UC-Berkeley, and several vendors were offering relational database products shortly thereafter.”
The relational model is based on the structure of a database. A database is simply a collection of one or more relations or tables with columns and rows. The use of set theory allows for data to be structured in a series of tables that has both columns and rows. Each column corresponds to an attribute of that relation, while each row corresponds to a record that contains data values for an entity.
The main elements of RDBMS are based on Ted Codd’s 13 rules for a relational system, the concept of relational integrity, and normalization. The three fundamentals of a relational database are that all information must be held in the form of a table, where all data are described using data values. The second fundamental is that each value found in the table columns does not repeat. The final fundamental is the use of Standard Query Language (SQL).
Benefits of RDBMS are that the system is simple, flexible, and productive. Because the tables are simple, data is easier to understand and communicate with others. RDBMS are flexible because users do not have to use predefined keys to input information. Also, RDBMS are more productive because SQL is easier to learn. This allows users to spend more time inputting instead of learning. More importantly, RDBMS’s biggest advantage is the ease with which users can create and access data and extend it if needed. After the original database is created, new data categories can be added without the existing application being changed.
There are limitations to the relational database management system. First, relational databases do not have enough storage area to handle data such as images, digital and audio/video. The system was originally created to handle the integration of media, traditional fielded data, and templates. Another limitation of the relational database is its inadequacy to operate with languages outside of SQL. After its original development, languages such as C++ and JavaScript were formed. However, relational databases do not work efficiently with these languages. A third limitation is the requirement that information must be in tables where relationships between entities are defined by values.
Today, the relational model is the dominant data model as well as the foundation for the leading DBMS products, which include IBM’s DB2 family, Informix, Oracle, Sybase, Microsoft’s Access and SQLServer, as well as FoxBase and Paradox. RDBMS represent close to a multibillion-dollar industry alone.
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