DBMS
Notes
Que & Ans
◾Diamond is used to represent the relationship.
For example : A female marry to one male and a male can marry to one female (Only in INDIAN Culture).
2. One to many relationship :-
◾When only one instance of entity at the left, and more than one instance of entity on the right associates with the relationship then this is known as a one to many relationship.
For Example : scientist can invent many inventions, but the invention is done by only the specific scientist.
For Example : Students enroll for one course, but a course can have any students.
For Example : Employee can assign by many projects and project can have many employees.
Read : ER Model
Relationship & its Types
27 August
2
What is relationship ? Describe different types of relationship ?
◾A relationship is used to describe the relation between entities.◾Diamond is used to represent the relationship.
Types of relationship :-
The types of relationship are as follows :1. One to one relationship :-
◾When only one instance of an entity is associated with the relationship, then it is known as one to one relationship.For example : A female marry to one male and a male can marry to one female (Only in INDIAN Culture).
2. One to many relationship :-
◾When only one instance of entity at the left, and more than one instance of entity on the right associates with the relationship then this is known as a one to many relationship.
For Example : scientist can invent many inventions, but the invention is done by only the specific scientist.
3. Many to one relationship :-
◾When more than one instance of the entity on the left, and only one instance of an entity on the right associates with the relationship then it is known as many to one relationship.For Example : Students enroll for one course, but a course can have any students.
4. Many to many relationship :-
◾When more than one instance of the entity on the left, and more then one instance of an entity on the right associates with the relationship then it is known as a many to many relationship.For Example : Employee can assign by many projects and project can have many employees.
Read : ER Model
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Thank u ptnr
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