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DBMS Articles
Page 25 of 27
Explain the concept of the traditional file system in DBMS?
A file system is a method of storing and organizing the computer files and the data they contain to make it easy to find and access them.Characteristics of file systemThe characteristics of file system are as follows −It is a group of files for storing the data of an organization.Each file is independent from one another.Each file is called a flat file.Files are designed by using the program written in programming languages such as C, C++.Disadvantages of file processing systemThere are so many disadvantages in the file processing system. These are explained below −Separated and isolated data.Duplication of data − ...
Read MoreWhat is the difference between data and information in DBMS?
Before understanding the difference between data and information, let’s have a look at the definitions of data and information with an example.DataData is the raw material that can be processed for any computing machine.For example − Employee name, Product name, Name of the student, Marks of the student, Mobile number, Image etc.InformationInformation is the data that has been converted into more useful or intelligent form.For example: Report card sheet.The information is needed for the following reasons −To gain knowledge about the surroundings.To keep the system up to date.To know about the rules and regulations of the society.KnowledgeThe human mind purposefully ...
Read MoreDistinguish between flat files and databases (dbms)?
Let’s discuss flat and database definition before understanding the difference between flat files and databases.Flat filesA flat file contains records which have no structured interrelationship. They are typically called as a text file, where all word processing, structure characters and markup have been removed. A flat file represents a table with a single record per line. Generally, it is a type of database that stores data in a plain text format.DatabaseThe related information when placed in an organized form that makes a database or an organized collection of related information is called a database.For example − Dictionary, Telephone directory etc.DifferencesFollowing ...
Read MoreSecurity, Integrity and Authorization in DBMS
Database SecurityDatabase security has many different layers, but the key aspects are:AuthenticationUser authentication is to make sure that the person accessing the database is who he claims to be. Authentication can be done at the operating system level or even the database level itself. Many authentication systems such as retina scanners or bio-metrics are used to make sure unauthorized people cannot access the database.AuthorizationAuthorization is a privilege provided by the Database Administer. Users of the database can only view the contents they are authorized to view. The rest of the database is out of bounds to them.The different permissions for ...
Read MoreCentralized Database Management System
A centralized database is stored at a single location such as a mainframe computer. It is maintained and modified from that location only and usually accessed using an internet connection such as a LAN or WAN. The centralized database is used by organisations such as colleges, companies, banks etc.As can be seen from the above diagram, all the information for the organisation is stored in a single database. This database is known as the centralized database.AdvantagesSome advantages of Centralized Database Management System are −The data integrity is maximised as the whole database is stored at a single physical location. This ...
Read MoreN-ary Relationship in Database
A relationship is an important part of any Entity relationship diagram as it shows the relation between two different entities. In an n - ary relationship, the n shows the number of entities in the relationship. It can be anything but the most popular relationships are unary, binary and ternary where the number of entities respectively are one, two and three.More information about Unary, Binary and Ternary relationships is as follows −Unary RelationshipWhen there is a relationship between two entities of the same type, it is known as a unary or recursive relationship. This means that the relationship is between ...
Read MoreFunctions in Oracle DBMS
The different types of functions in Oracle are −Oracle String FunctionsOracle Numeric FunctionsOracle Date FunctionsMore details about these functions are given as follows −Oracle String FunctionsThe following are the Oracle String Functions −ASCII(str)This function returns the ASCII or numeric value of the first word in the string str provided. If it is an empty string, it returns 0. For example:SQL> SELECT ASCII('Apple'); +---------------------------------------------------------+ | ASCII('Apple') | +---------------------------------------------------------+ | 65 | +---------------------------------------------------------+ 1 row in set (0.00 sec)This returns the ASCII value of A i.e. 65 as it is the first character in the string.CONCAT(str1, str2…..strn)This function returns the string that ...
Read MoreCursors in Oracle DBMS
When a SQL statement is executed in Oracle, the temporary context area is created. This area contains all the relevant information relating to the statement and its execution. The cursor is a pointer to this context area and allows the PL/SQL program to control this area.There are two types of Cursors.Implicit CursorsExplicit CursorsLet us begin with Implicit Cursors −Implicit CursorsWhenever an SQL statement is executed, the implicit cursors are automatically created. This happens if there is no explicit cursor for the particular statement. Implicit cursors cannot be controlled by the programmers.There are many different attributes for Implicit Cursors. Some of ...
Read MoreDDBMS Components
The contents of a distributed database are spread across multiple locations. That means the contents may be stored in different systems that are located in the same place or geographically far away. However, the database still appears uniform to the users i.e the fact that the database is stored at multiple locations is transparent to the users.The different components of a distributed database are −Let us now discuss them one by one −UsersThere are many users who use the distributed database. For them, the fact that the database is spread across multiple locations is transparent and they perceive the database ...
Read MoreUnary or Recursive Relationship
When there is a relationship between two entities of the same type, it is known as a recursive relationship. This means that the relationship is between different instances of the same entity type.Some examples of recursive relationship can be shown as follows −An employee can supervise multiple employees. Hence, this is a recursive relationship of entity employee with itself. This is a 1 to many recursive relationship as one employee supervises many employees.A person can have many children who are also persons. Hence, this is a recursive relationship of entity person with itself. This is a 1 to many recursive ...
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