Classification of database management system
Database management systems can be divided into different ways. Namely- Client Server, Distributed Database and Web Enabled Database.
Client server database
A client-server database is a database system that interacts with a centrally controlled server. The original database is permanently stored on the server. From a distance, different users can access the database as part of a computer network system.
In this case database users are called client / terminal. In the client server system only one database server is stored which is called back end.
Client computers have only forms and reports called front end. In this case, more than one user can work through the database connection at the same time or at different times with the help of front end. Using the client / terminal server's resources, the server can assist the client in processing.
The client sends a request to the server to receive a service; The server provides data or services in accordance with client requests and other rules. The client can never make any changes or additions to the database. In this case only the database administrator determines the structural changes of the database, number of users etc.
The following materials exist in a client server model.
Client: A client is a machine (workstation or PC) that runs a front-end application. It plays a helpful role in performing tasks directly with the user through keyboard, monitor and so on.
Server: A server is a machine that runs server software (such as Oracle, SQL Server) and handles essential functions in share data access. Serves as a server back-end.
Distributed databases are multiple database systems connected to a centrally controlled server through a network. This method can have a central server (central server) and one or more sub-servers (sub-servers) or workstations under it.
Database modification, editing etc. is done individually in each sub-server / workstation including central server. Central databases stored on central servers are modified or updated according to the latest state of the workstation databases.
The server's central database may modify or modify the data text and description language of the database of sub-servers. In this way, the distributed database system collects, manages and controls the latest data from the databases of the workstations through the server's central database.
The client server approach is preferred for distributed database management. Because workstations can have one or more clients.
The funny thing here is that even if the workstation does not have a network connection with the central server, the workstation clients can work without any hassle. Because the sub-server or workstation is a separate client server database system.
Workstation clients only log in to the workstation database. The central-server is updated according to the latest status of the sub-server whenever the sub-server gets the network connection with the sub-server whenever it gets the network connection of the sub-server.
Distributed databases have two main features
i. Distribution: Distributing the entire work of the original database to different ends / workstations.
ii. Logical Co-relation: If necessary, different workstations can maintain the relationship through ATM (Asyncronous Transmission Mode). In this case the server fully cooperates.
Components of a distributed database
Network Connection Manager, Transaction Manager, Query Processor, Recovery Manager, System Catalog.
A database that can be accessed remotely on a platform via a web interface from anywhere connected to the Internet is called an enabled database.
In other words, a database is a web-enabled database that can be used to interactively access information, create queries, place orders, report and track records, and record through the Internet and web browsers.
The basic components of a web-enabled database are:
Webpages and software to provide a full-time Internet connection, a web server, a firewall, active application.
Web enabled databases work in three tiers or layers. Namely: - 1. Presentation layer, 2. Middleware layer, 3. Database layer
The names of some of the most popular web enabled database servers at present-
Oracle, Microsoft SQL Server, MySQL etc.