select the attributes which made up of more than one single attribute.

get select the attributes which made up of more than one single attribute. from screen.

The attributes made up of more than one single attributes are called :

multiple choice questions and answers on DBMS e.g. The attributes made up of more than one single attributes are called :

Question

The attributes made up of more than one single attributes are called :

A Derived attribute

B Composite attribute

C Single value attribute

D Multi value attribute

Answer & Explanation

Option: [B] Advertisement

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ER Model

ER Model - Basic Concepts, The ER model defines the conceptual view of a database. It works around real-world entities and the associations among them. At view level, the ER model is cons

ER Model - Basic Concepts

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DBMS For GATE Exams

178 Lectures 14.5 hours

Arnab Chakraborty More Detail

The ER model defines the conceptual view of a database. It works around real-world entities and the associations among them. At view level, the ER model is considered a good option for designing databases.

Entity

An entity can be a real-world object, either animate or inanimate, that can be easily identifiable. For example, in a school database, students, teachers, classes, and courses offered can be considered as entities. All these entities have some attributes or properties that give them their identity.

An entity set is a collection of similar types of entities. An entity set may contain entities with attribute sharing similar values. For example, a Students set may contain all the students of a school; likewise a Teachers set may contain all the teachers of a school from all faculties. Entity sets need not be disjoint.

Attributes

Entities are represented by means of their properties, called attributes. All attributes have values. For example, a student entity may have name, class, and age as attributes.

There exists a domain or range of values that can be assigned to attributes. For example, a student's name cannot be a numeric value. It has to be alphabetic. A student's age cannot be negative, etc.

Types of Attributes

Simple attribute − Simple attributes are atomic values, which cannot be divided further. For example, a student's phone number is an atomic value of 10 digits.Composite attribute − Composite attributes are made of more than one simple attribute. For example, a student's complete name may have first_name and last_name.Derived attribute − Derived attributes are the attributes that do not exist in the physical database, but their values are derived from other attributes present in the database. For example, average_salary in a department should not be saved directly in the database, instead it can be derived. For another example, age can be derived from data_of_birth.Single-value attribute − Single-value attributes contain single value. For example − Social_Security_Number.Multi-value attribute − Multi-value attributes may contain more than one values. For example, a person can have more than one phone number, email_address, etc.

These attribute types can come together in a way like −

simple single-valued attributes

simple multi-valued attributes

composite single-valued attributes

composite multi-valued attributes

Entity-Set and Keys

Key is an attribute or collection of attributes that uniquely identifies an entity among entity set.

For example, the roll_number of a student makes him/her identifiable among students.

Super Key − A set of attributes (one or more) that collectively identifies an entity in an entity set.Candidate Key − A minimal super key is called a candidate key. An entity set may have more than one candidate key.Primary Key − A primary key is one of the candidate keys chosen by the database designer to uniquely identify the entity set.

Relationship

The association among entities is called a relationship. For example, an employee works_at a department, a student enrolls in a course. Here, Works_at and Enrolls are called relationships.

Relationship Set

A set of relationships of similar type is called a relationship set. Like entities, a relationship too can have attributes. These attributes are called descriptive attributes.

Degree of Relationship

The number of participating entities in a relationship defines the degree of the relationship.

Binary = degree 2 Ternary = degree 3 n-ary = degree

Mapping Cardinalities

Cardinality defines the number of entities in one entity set, which can be associated with the number of entities of other set via relationship set.One-to-one − One entity from entity set A can be associated with at most one entity of entity set B and vice versa.

One-to-many − One entity from entity set A can be associated with more than one entities of entity set B however an entity from entity set B, can be associated with at most one entity.

Many-to-one − More than one entities from entity set A can be associated with at most one entity of entity set B, however an entity from entity set B can be associated with more than one entity from entity set A.

Many-to-many − One entity from A can be associated with more than one entity from B and vice versa.

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Types of Attributes

Attributes in DBMS are the descriptive properties owned by each entity of an entity set. Types of attributes in DBMS- Simple attributes, Composite attributes, Single valued attributes, Multi valued attributes, Derived attributes, Key attributes

Types of Attributes | DBMS

Database Management System

Attributes in ER Diagram-

Before you go through this article, make sure that you have gone through the previous article on Introduction to ER Diagrams.

Attributes are the descriptive properties which are owned by each entity of an Entity Set.

There exist a specific domain or set of values for each attribute from where the attribute can take its values.

Types of Attributes-

In ER diagram, attributes associated with an entity set may be of the following types-

Simple attributes

Composite attributes

Single valued attributes

Multi valued attributes

Derived attributes Key attributes

1. Simple Attributes-

Simple attributes are those attributes which can not be divided further.

Example-

Here, all the attributes are simple attributes as they can not be divided further.

2. Composite Attributes-

Composite attributes are those attributes which are composed of many other simple attributes.

Example-

Here, the attributes “Name” and “Address” are composite attributes as they are composed of many other simple attributes.

3. Single Valued Attributes-

Single valued attributes are those attributes which can take only one value for a given entity from an entity set.

Example-

Here, all the attributes are single valued attributes as they can take only one specific value for each entity.

4. Multi Valued Attributes-

Multi valued attributes are those attributes which can take more than one value for a given entity from an entity set.

Example-

Here, the attributes “Mob_no” and “Email_id” are multi valued attributes as they can take more than one values for a given entity.

5. Derived Attributes-

Derived attributes are those attributes which can be derived from other attribute(s).

Example-

Here, the attribute “Age” is a derived attribute as it can be derived from the attribute “DOB”.

6. Key Attributes-

Key attributes are those attributes which can identify an entity uniquely in an entity set.

Example-

Here, the attribute “Roll_no” is a key attribute as it can identify any student uniquely.

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Summary

Article NameTypes of Attributes | DBMS

DescriptionAttributes in DBMS are the descriptive properties owned by each entity of an entity set. Types of attributes in DBMS- Simple attributes, Composite attributes, Single valued attributes, Multi valued attributes, Derived attributes, Key attributes

AuthorAkshay Singhal

Publisher NameGate Vidyalay

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