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A model in database system mostly defines the organisation of data or structure and a set of operations on that data. Relational model is a easy model in which database is represented as a collection of "Relations", where every relation is represented by a two dimensional table. Therefore, because of its simplicity it is most commonly used. The following table shows a simple relation:
PERSON_ID
NAME
AGE
ADDRESS
1
Sanjay Prasad
35
b-4,Modi Nagar
2
Sharad Gupta
30
Pocket 2, Mayur
Vihar.
3
Vibhu Datt
36
c-2, New Delhi
Figure: A Sample Person Relation
Following are some of the benefits of relational model:
The easy tabular representation of database helps the user define and question the database conveniently. For example, you can simply find out the age of the person whose first name is "Vibhu".
As the database is a collection of tables, new data can be added and removed easily. Also, manipulation of data from several tables can be done simply using several basic operations. For instance, we can add a telephone number field in the table at Figure.
In relational databases the relational algebraic operations are used to influence database. These are mathematical operations and make sure accuracy (and less of ambiguity) as compared to other models.
why are older data models are being replaced by new data models
Explain the steps for reduction of E-R model into relational model. Ans:(a) Entity set in E-R model will be considered as table name in relational Model. (b) Attributes of e
Outer Join: The use of Outer Join is that it still joins those tuples that do not have matching values in common columns are also contained in the result table. Outer join places
Hierarchical model is also known by? A hierarchical model is also known as a Tree structure.
Ask question #Minim 100 words accepted#what is recovery management component in database management system and how it is useful
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Describe the different RAID levels. Discuss the choices of the different RAID levels for different applications. Ans: There are several combinations of these approa
Cardinality of Relationship One-to-One Only one entity of the first set is linked to only one entity of the second set. E.g. A teacher teaches a student. Only one teacher
What subschema expresses ? A subschema expresses the external view. (External schemas are called also called as subschemas)
A B-tree of order how much children m has maximum ? m has maximum m mchildren in a B tree.
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