Advanced databases plays a vital role in functioning of modern organisation. Every day we all are dealing with some database applications like shopping at a super market, withdrawing cash using ATM, ordering a book online etc. Database technology not only used to improve our daily operations but also the quality of decisions that affects our daily life. Database environment encapsulates one or more databases. This encapsulation allows us to perform the group operations between multiple databases in a single transaction. Database environment is surrounded by different types of relations, tables, file models, time sharing models to store, access and update the data in the organizational database.
Database contain a flood of data about many aspects of our life. Such as consumer preferences, telecommunications usage, credit history etc. Databases contain these sorts of facts as well as non conventional facts such as photographs, fingerprints etc.
Some important properties of database are discussed below.
(a) Persistent:- It means data reside on stable storage such as a magnetic disk. It depends upon the intended usage.
(b) Shared:– It means the database have multiple uses and uses.
(c) Interrelated:– It means that data stored as separate units can be connected to provide a whole picture.
(d) Entity:– It is a cluster of data usually about a single subject that can be accessed together.
File Processing System:
File processing system is a type of system which is used to store and organize the information in the database. It is the process of creating, storing and accessing the content of files. It can be used to save a new file in the processing system. Through this file processing system, we can create new files and save the existing files.
Advantages File Processing System
The advantages of a file processing system is listed below.
(a) It is simple to use.
(b) It is less expensive.
(c) It fits the needs of many small businesses and home users.
(d) Popular file management systems are packaged along with the operating systems.
(e) Good for database solutions.
Disadvantages of File Processing System
There are certain disadvantages in file processing system.
(a) It typically does not support multiuser access.
(b) It is limited to smaller databases.
(c) It has limited functionality.
(d) It has redundancy.
(e) It has integrity issues.
Main Services of Relational Database Management System
The main services of Relational Database Management System are listed below.
(a) Data storage, data retrieval and data update.
(b) User accessible catalog.
(c) It supports the transaction.
(d) It controls the concurrency in the database.
(e) It is recoverable.
(f) Only authorized users can view access the data.
(g) It supports the data communication.
(h) It supports the data independence.
Need of Database
There are certain advantages of using the database.
(a) It has the chance of maximum reduction of redundancy.
(b) In database, data can be used for more than one application.
(c) It supports standardization.
(d) It has the better security option.
(e) The integrity of data is independent of several applications.
(f) Here the data can be used directly.
Time Sharing Model
Time sharing model is the main frame and terminal of database. Its environment consists of the mainframe and minicomputer. The components of time sharing model are operating systems. Here, DBMS and applications are running on a single computer. It has the interaction through terminals. The user interface in time sharing model is generated by mainframe or minicomputer. It has one or more cooperative processors for processing system.
File Server Model
File server model consists of server and personal computers. It has the environment consists of file server and work stations. The components of a file server model are DBMS and application programs which are separated from the database. It has the interaction through workstations. The screen layout is generated by workstations. In file server model, all processing is carried out by one or more intelligent workstations.
Normally data integrity means consistency, validity and accuracy of data in a database. Normally, there are four types of data integrity. These are listed below.
(a) Table level integrity
(b) Field level integrity
(c) Relationship level integrity
(d) Business rules
Physical data independence.
Physical data independence is the ability to modify re internal schema without having the change to the conceptual or external schema. In physical data independence, the conceptual schema covers the users from changes in the physical storage of data. Physical data independence indicates that the physical storage structures or devices used for storing the data could be changed without necessitating a change in the conceptual view of any of the external views.
Components of a run time database manager.
The run time database manager is normally called as the database control system. It has the following components.
(a) Authorization control checks the authorization of users.
(b) Command processor processes the queries passed by authorization control module.
(c) Integrity checker checks the integrity constraints so that only valid data can be entered into a database.
(d) Query optimizer determines an optimal strategy for the query execution.
(e) Transaction manager ensures that the transaction properties are maintained by the systems.
(f) The scheduler provides an environment in which multiple users can work on.
(g) Data manager is responsible for the actual handling of data in the database.