The main objective of the database is to ensure that data can be stored and retrieved easily and effectively. It is a compilation of data (records) in a structured way. In a database, the information is stored in a tabular form where data may or may not interlinked. Hence we cam say that basically database is a compilation of database files and each database file is further a collection of records.
The chronological order of the development of DBMS is as follows 1. Flat Files (1970s-1990s) 2. Hierarchical (1970s-1990s) 3. Network (1970s- 1990s) 4. Relational (1980s-present) 5. Object-Oriented (1990s- present) 6. Object-Relational (1990s-present) 7. Web enabled (1990s-present) 1.Flat Files (1970s-1990s) : Flat files database is a database that stores information in a single file or table. In text file, every line contains one record where fields either have fixed length or they are separated by commas, whitespaces, tabs or any records and they cannot contain multiple tables as well. 2.Hierarchical (1970s-1990s) : As the name indicates, hierarchical database contains data in a hierarchically-arranged data. More Perceptively it can parent can have many children but one child can only have one parent i. e.,; one-to-many relationship. Its hierarchical structure contains levels or segments which are equivalent to the file system’s record type. All attributes of a specific record are listed under the entity type. 3.Network database (1970s -1990s) : The inventor of network model is Charles Bachmann. Unlike hierarchical database model, network database allows multiple parent and child relationships i. e., it maintains many-to many relationship. Network database is basically a graph structure. The network database model was created to achieve three main objectives: . To represent complex data relationship more effectively. . To improve the performance of the database. . To improve a database standard. 4.Realationl database (1980s-present) : Relationship database model was proposed by E. F. Codd. After the hierarchical and network model the birth of this model was huge step ahead. It allows the entities to be related through a common attribute. In the table there are alternative keys. This property makes this model extremely flexible. 5.Object – oriented database (1990s -present) : Object-Oriented database management system is that database system in which the data or information is presented in the form of objects, much like in object-Oriented programming language. Furthermore, object oriented DBMS also facilitate the user by offering transportation support, language for various queries, and indexing options. Also, these database systems have the ability to handle data efficiently over multiple servers. Unlike relationship database object-oriented database works in the framework of real programming language like JAVA or C++. 6. Object- relationship database (1990s-present) : Defined in simple teams, an object relationship database management system displays a modified object- oriented user- display over the already implemented relationship database management system. When various software interact with this modified- database management system, they will customarily operate in a manner such that data is assumed to be saved as objects. The basic working of this database management system is that is translated the useful data into organized tables distributed in rows and columns, and from then onwards, it manages data thr same way done in s relational database system. Similarly, when the data is to be accessed by the user, it is again translated from processed to complex form.