Skip to main content

What is Relational Database Model


Relational Database Model:


What is Relational Database Model

1) The relational database model is developed by “Edgar F. Codd” at IBM in 1970.
2) The relational Database Model used the basic concept of a relation or table.
3) A table is a collection of records and each record in a table Contains the same fields.
4) Every row or entity (called Tuple) must have a unique identification or key based
on the data.

What is Data Base Model

5) The different tables may have the common column name (Attribute), but a single
table must not Contain multiple columns (Attributes) with the same name.
6) The relationship between the two tables is implemented using a common and
unique attribute in the tables.
7) Columns are attributes that belong to the entity modeled by the table.
8) order of rows (tuples/entity) and columns (attributes) is not important.
9) But every Tuple must be unique. It means that for every record or Tuple in a table
there is something that uniquely identified ¡t from any other Tuple.
10) Each cell can contains only single value (value for attribute).
1) The column (attribute) contains same types of values for every Tuple.
) The two tables in the database must not have the same name. they can have some
column name in common.
Relational Database Management System (RDBMS)
RDBMS is a software system that provides access to a relational database.
RDBMS ¡s based on relational database model introduced by E. F. Codd in 1970.

Relation

1) Generally a table with columns and rows is a relation.
2) All data and relationships are represented ¡n two dimensional table called a relation.
3) In other words, it represents the relation between rows and columns of a t
dimensional table.
4) A relation consists of number of records or row-wise information and column-wise .
information.

Attributes:

1) An attribute is a named column of a relation.
2) In the relational model, relations are used to hold information about the objects to
be represented in the database.
3) A relation is represented as a two-dimensional table in which the rows of the table corresponds to individual records and the table columns correspond to attributes.
4) Attributes can appear in any order and the relations will still be the same relations.

Domain:

1) A domain is the set of allowed values for one or more attributes.
2) A domain defines the type of data represented by an attribute.
3) A domain is the set of all possible values that an attribute may validly contain.
4) Every attribute has some pre-defined value scope, known as domain.
5) For Example: in college database, domain for “Gender” column consists of one

What is Data Independence in Database

two values “Male” and “Female”.
6) Similarly, domain for “CityName” column consists of range of valid city names of
student studying in the college from Amravati Division. (Domain of “CityName”
may includes “Amravati, Akola, Yavatmal, Washim, Buldhana).
7) Therefore every table that has a column “CityName” can contain only those values

Popular posts from this blog

How do I make a blockchain account and make money ?

How do I came upon Blockchain? Setup non-public Ethereum Blockchain Network with Multiple Nodes with ten lines of code Step 1: Setup. Open the terminal in one machine and run the below command. ... Step 2: Installation. Step 3: produce Account. Step 4: Genesis File. Step 5: begin Node. Step 6: Connect. Step 7: Let's Mine. How do I deposit cash into Blockchain? Create your free pocketbook currently. Your Blockchain pocketbook can generate a novel bitcoin and Bitcoin money address every time you wish to receive funds. To request funds victimization associate degree address, merely click request at the highest of your pocketbook. within the currency drop, choose that digital plus you'd prefer to request. What is a Blockchain account? A blockchain pocketbook could be a digital wallet that permits users to manage bitcoin and ether. Blockchain pocketbook is provided by Blockchain, a package company based by Peter Smith and Nicolas Cary. How am i able to ...
Read more

How do I earn from data entry at home through PillowBux?

How do I earn from data entry at home through PillowBux? Pillow Bux: a way to create cash and find referrals for complimentary Sign up currently Pillow Bux could be a completely free service in its use so additionally the registration is totally free and takes simply over two minutes to finish all the steps needed for registration. we have a tendency to don't oblige anyone to register (usage infos), however if you furthermore may need to do to create cash on-line with Pillow Bux. then visit pillowbux web site. How to create cash on-line with Pillow Bux You earn cash by writing captchas and each captcha is value $0.0001. you simply would like time and you have got to hold back. The a lot of you employ this website, the a lot of you’ll earn. the location offers too a referral program that pays you twenty fifth for each referral and for the primary 5 it’ll provide you with $5 ($1 every one). Once you reach 30k captchas (that are value $3) the site’ll provide yo...
Read more

What is Normalization in the database

What is Normalization in the database Normalization : 1). Normalization is the process of organizing the tables to minimize data redundancy 2)Redundancy   is storing the same data item in more than one place. Database normalization is a design technique) by which an existing database is modified to minimize redundancy and dependency of data. 4) Edgar F. Codd introduced the concept of normalization in 1970.Objectives   of normalization: Edgar F. Codd stated the objectives of normalization are as follows. To free the collection of relations from undesirable insertion, update and deletion dependencies. 2) To reduce the need for restructuring the collection of relations as new types of data are introduced, and thus increase the life span of application programs. To make the relations model more informative to users. 4 To make the collection of relations neutral to the query statistics. is normalization? Explain 1 NF with suitable example _____ ...
Read more