AdminNovember 21, 2020comment (0)Uncategorized

Characteristics of DBMS

  • It uses a digital repository established on a server to store and manage the information.
  • It can provide a clear and logical view of the process that manipulates data.
  • DBMS contains automatic backup and recovery procedures.
  • It contains ACID properties which maintain data in a healthy state in case of failure.
  • It can reduce the complex relationship between data.
  • It is used to support manipulation and processing of data.
  • It is used to provide security of data.
  • It can view the database from different viewpoints according to the requirements of the user.
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AdminNovember 21, 2020comment (0)Uncategorized

Database Management System

  • Database management system is a software which is used to manage the database. For example: MySQL, Oracle, etc are a very popular commercial database which is used in different applications.
  • DBMS provides an interface to perform various operations like database creation, storing data in it, updating data, creating a table in the database and a lot more.
  • It provides protection and security to the database. In the case of multiple users, it also maintains data consistency.

DBMS allows users the following tasks:

  • Data Definition: It is used for creation, modification, and removal of definition that defines the organization of data in the database.
  • Data Updation: It is used for the insertion, modification, and deletion of the actual data in the database.
  • Data Retrieval: It is used to retrieve the data from the database which can be used by applications for various purposes.
  • User Administration: It is used for registering and monitoring users, maintain data integrity, enforcing data security, dealing with concurrency control, monitoring performance and recovering information corrupted by unexpected failure.
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AdminNovember 21, 2020comment (0)Uncategorized

What is Database

The database is a collection of related or inter-related data which is used to retrieve, insert and delete the data efficiently. It is also used to organize the data in the form of a table, schema, views, and reports, etc.

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AdminOctober 19, 2020comment (0)DBMS

Schema and Instance in DBMS

 12 Apr  Admin

Schema 

A schema is the complete design of database it is also known as intension. It is the collection of named objects.

Design of a database is called the schema. Schema is of three types: Physical schema, logical schema and view schema.

The database system has various schemata separated according to the levels of abstraction :-

  1. The physical schema is the lowest level of a schema which describes how the data stored on the disk or the physical storage.
  2. The logical schema is the intermediate level of a schema which describes the structure of the database to the database designers. It also specifies what relationship exists between the data.
  3. The external schema or subschema is the highest level of a schema which defines the views for the end users.

Instance

An instance is the information collected in a database at some specific moment, and it is also known as state or extension. It is a snapshot where the current state or occurrence of a database is framed at that moment.

The data stored in database at a particular moment of time is called instance of database. Database schema defines the variable declarations in tables that belong to a particular database; the value of these variables at a moment of time is called the instance of that database.

Schema and instance are somehow related, a schema is the initial state of the database where the database is designed at first. On the other hand, an instance is a state when data is loaded into the database or when any change is acquired by the corresponding database. Schema is the detailed description of the structure of database whereas the information stored at a specific moment in a database is known as an instance.

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AdminSeptember 3, 2020comment (0)DBMS

Data Abstraction in DBMS

 03 Sep  Admin

Abstraction,in general, is the process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics.Database systems are made-up of complex data structures. To ease the user interaction with database, the developers hide internal irrelevant details from users. This process of hiding irrelevant details from user is called data abstraction.

There are mainly 3 levels of data abstraction:

Physical level: Physical level is the lowest level of data abstraction which describes how data is actually stored in database. You can get the complex data structure details at this level.

Logical level: Logical level is the middle level of 3-level data abstraction architecture which describes what data is stored in database.

View level: Highest level of data abstraction is view level which describes the user interaction with database system.

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