Relational database


<<Previous   Next>>
Relational database - June 17, 2010 at 11:20 AM by Rajmeet Ghai

What is Rational database? Flat database vs. Rational database
Features of Rational database
Dr. Codd defined thirteen standards which must be met before a database can be considered to be a relational database. What was that?
Explain how data is arranged in a rational database with an example.

What is Rational database? Flat database vs. Rational database

A relational database looks for relativity in the database. This means that it has a set of tables with predefined meanings and it matches data using some common attributes found in the data set.

A flat file database restricts user to define the data types and columns one table at a time. Any plain text file could be an example of this. On the other hand relational database allows data types and columns to be defined for multiple tables and thereby permitting a relationship between them.

Features of Rational database

  • A relational database is created and defined using SQL queries.
  • It allows the columns to have constraints like primary key, NOT NULL and foreign keys for consistency and integrity of data.
  • It allows additional features like stored procedures, indices for faster data retrieval.
  • It allows you to perform server complex calculations using an array of operators.

Dr. Codd defined thirteen standards which must be met before a database can be considered to be a relational database. What was that?

  • Relational capabilities must be used in order to manage such databases.
  • Information in a database should be interpreted only through values of tables, columns etc
  • The information can be accessed using a combination of the table name, primary key value, and column name.
  • support for the treatment of null values, distinct from default values and independence of domain should be provided.
  • In order to describe a database, logical level like tables should be made use of.
  • At least one supported language must have a well-defined syntax and be comprehensive. It must support data definition, manipulation, integrity rules, authorization, and transactions.
  • The system should be capable of updating views
  • It should allow set-level inserts, updates, and delete apart from set-level retrievals
  • On altering physical access methods or storage structures, Application programs and ad hoc programs should be unaffected to maintain Physical data independence
  • In order to maintain logical data independence, application programs and ad hoc programs shouldn’t be logically affected.
  • The database should be capable of defining integrity rules
  • On distributing and redistributing data, Application programs and ad hoc requests are logically unaffected.
  • Integrity rules cannot be bypassed using lower-level languages

Explain how data is arranged in a rational database with an example. 

Data in a relational database is arranged with the help of tables. A table is a logical entity that has columns and rows. Each table has values that represent data.

Example:

Table employee has the fields id, name, salary. Here, the columns are id, name and salary while their values will be data.

-Introducing data manipulation language(DML)

<<Previous   Next>> 
What is RDBMS? Explain its features

RDBMS is a database management system based on relational model defined by...RDBMS stands for Relational Database Management System..........

Oracle database objects

Tables, indexes, views, synonyms, sequences, ... In the terms of a relational database, one can call a table as an entity and the.......

Oracle interview questions and answers

Explain Row level and statement level trigger, What is a join, explain the types of joins?, Differences between CHAR and NCHAR in Oracle, Differences between DATE and TIMESTAMP in Oracle, Explain the attributes of implicit cursor.............



Write your comment - Share Knowledge and Experience


 

 
Interview questions
Latest MCQs
» General awareness - Banking » ASP.NET » PL/SQL » Mechanical Engineering
» IAS Prelims GS » Java » Programming Language » Electrical Engineering
» English » C++ » Software Engineering » Electronic Engineering
» Quantitative Aptitude » Oracle » English » Finance
Home | About us | Sitemap | Contact us | We are hiring