Object oriented databases have now become very popular as they provide a greater degree of flexibility in data storage and also provide a resource efficient storage mechanism. The data storage in the object oriented databases is in the form of objects instead of storing as rows and columns.
The integration and connectivity of individual systems provide support to connect stand alone machines. In the current environment, the databases are all linked at the backend. This provides for client-server database architecture which gives a whole new dimension to existing database structure.
The databases today are based on client-server architecture and provide support for multimedia content. They are huge in size as storage costs are not of much concern today. Data warehouses act as archives and analytical tool for the historical data.
Relational database was a revolution in the field of databases. The idea of having a tabular structure composed of rows and columns was a ground breaking proposition to make storage and retrieval easier than ever before.
Peter Rob in his book describes the relational database in terms of storage and representation. The relational database model allows the designer to focus on the logical representation of the data and its relationships than the physical storage details. The tables are all logical, having the similar physical storage mechanisms at the backend.
The relational databases are based on a row-column structure, each column being an attribute and a row as record. Each record or row can have a number of attributes for a particular record.
Each table is referred to as relation, and hence called relational database, having a unique attribute(s) which make up the primary key. Each table is linked to one or more tables through the primary key and foreign key architecture.
By structure, the relational database does not have any cap on storage limit, but due to storage limitations, they may act as constraints to the system.
The relational databases use the concept of indexing for making the search faster and easier. The indexes are not the keys, but are attributes used for faster searching. They are the attributes which are frequently used for searching.
The structure of relational databases can be seen in the following Entity Relationship Diagram and Relational Schema showing the entities and their attributes along with the relationships among them.
Relational Databases Vs Other Databases
The relational database is different from other databases in that the storage mechanism of relational databases is based on tables.
1. The flat file uses different files to store data
2. Object-oriented uses objects as storage units
3. Hierarchical makes and traces data based on their hierarchies
4. Network is similar to hierarchical but the hierarchies are in both directions, that is many parents can have a common child
5. Hybrid or Object-Relational Databases are becoming popular too. They have a mixed structure with the features of both the relational and object-oriented databases
E F Codd was a researcher at IBM. He proposed the model for the modern relational Database Management System. He presented the twelve points that any ideal relational