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Table of contents
1.
Introduction
2.
ER model in DBMS 
3.
What is Multivalued Attribute in DBMS?
4.
What are the Problems Associated with Multivalued Attributes?
5.
Examples of Multivalued Attribute
5.1.
Coder Example 
5.2.
CODE
5.2.1.
OUTPUT
5.2.2.
Person Example
5.3.
CODE
5.3.1.
OUTPUT
6.
Pros and Cons of Multivalued Attribute
6.1.
Pros of Multivalued Attribute
6.2.
Cons of Multivalued Attribute
7.
Difference Between Single-Valued & Multivalued Attributes
8.
Frequently Asked Questions
8.1.
What is multi valued attribute in relational schema?
8.2.
How are multivalued attributes represented in an ER model?
8.3.
Can a multivalued attribute be a primary or foreign key in a database?
8.4.
How do you handle duplicate values in a multivalued attribute?
8.5.
How do multivalued attributes relate to weak entities?
9.
Conclusion
Last Updated: Jul 3, 2024
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Multivalued Attributes in DBMS

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Speaker
Prerita Agarwal
Data Specialist @
23 Jul, 2024 @ 01:30 PM

Introduction

Have you ever struggled with managing your data in a Database? Multivalued attributes might be the solution. Have you ever wondered how to use multivalued attributes in your database schema?

multivalued attribute

You can improve data organisation and management by properly using multivalued attributes in your database. In this article, we'll discuss the features and properties of Multivalued Attributes in DBMS along with some real-world examples. So let's discover the world of multivalued attributes.

ER model in DBMS 

ER model in Also see, DBMS stands for Entity-Relationship model. It is a high-level data model used to represent a logical database view. It defines the entities in the system and the relationships between them. ER, diagrams sketch out the database design by defining the entities and their attributes and showing the relationships between them. ER modelling is a systematic process of designing and implementing a database system.

In ER modelling, there are four types of attributes:

  1. Simple Attribute: A single-valued attribute.
     
  2. Composite Attribute: An attribute having multiple simple attributes.
     
  3. Multivalued Attribute: An attribute with multiple values for a single entity instance.
     
  4. Derived Attribute: An attribute that can be derived from other attributes in the entity.
     

In ER modelling, multivalued attributes are represented with double ovals. Entities are used to manage multivalued attributes in ER modelling.

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What is Multivalued Attribute in DBMS?

Multivalued attributes are those attributes that have more than one value. They are used to represent entities that have more than one value for a given attribute. In an ER diagram, multivalued attributes are indicated by double lines joining the attribute to the entity. A table's primary key cannot be a multivalued attribute. A separate table can represent them. Each row contains a single attribute value and a foreign key connecting it to the original entity.

What are the Problems Associated with Multivalued Attributes?

Multivalued attributes in a database can cause several issues. They complicate the database design, making it harder to manage and query. Storing multiple values in a single attribute violates the principles of normalization, leading to redundancy and inconsistency. This can result in difficulties in performing searches, updates, and deletions, as operations must handle multiple values correctly. Additionally, indexing and optimizing queries become more complex, potentially degrading performance. Ensuring data integrity and enforcing constraints are also more challenging with multivalued attributes, increasing the risk of data anomalies and errors. Overall, they complicate database management and reduce efficiency.

Examples of Multivalued Attribute

Coder Example 

A "programming language" is a multivalued attribute. This is because a coder can have experience in multiple programming languages. For example, a coder may know how to code in Java, Python, or C++. It would be necessary to store all of these languages as values for that coder's "ProgrammingLanguages" attribute in a database table. 

coder example

CODE

Step 1:  Creating the Coder's table.

CREATE TABLE Coders (
   CoderID INT PRIMARY KEY,
   CoderName VARCHAR(255),
   ProgrammingLanguages VARCHAR(255),
   ProgrammingLanguages_Type VARCHAR(255)
);


Step 2: Now insert some entries into the Coder's table

INSERT INTO Coders (CoderID, CoderName, ProgrammingLanguages, ProgrammingLanguages_Type) 
VALUES (1, 'Ninja-1', 'Python, Java, C++', 'multivalued'),
       (2, 'Ninja-2', 'Java, HTML, CSS', 'multivalued'),
       (3, 'Ninja-3', 'Python', 'single valued'),
       (4, 'Ninja-4', 'PHP, Ruby', 'multivalued');


Step 3: To display the contents of the Coder's table

SELECT * FROM Coders;

OUTPUT

output table

Person Example

Another example of a multivalued attribute can be the hobbies of an individual. Let's say we have an entity called "Person"; one of its attributes is "Hobbies". People can have various hobbies, so "Hobbies" is a multivalued attribute.

person example

CODE

Step 1: Creating person table 

CREATE TABLE Person (
    ID INTEGER ,
    Name TEXT ,
    Age INTEGER,
    Hobbies TEXT
);


Step 2: Inserting different hobbies

INSERT INTO Person (Name, Age, Hobbies) VALUES ('Ninja1', 19, 'Coding, Singing, Sleeping');
INSERT INTO Person (Name, Age, Hobbies) VALUES ('Ninja2', 22, 'Swimming, Cooking, Dancing');
INSERT INTO Person (Name, Age, Hobbies) VALUES ('Ninja3', 20, 'Photography, Reading, Watching Movies');


Step 3: Printing the table

SELECT * FROM Person;

OUTPUT

output table

Pros and Cons of Multivalued Attribute

Pros of Multivalued Attribute

  1. It avoids data duplication.
     
  2. It increases data accuracy and stability.
     
  3. It allows better organization of data.
     
  4. It will enable easier querying and sorting of data.
     
  5. It improves data recovery speed and efficiency.

Cons of Multivalued Attribute

  1. It makes data modelling more complex and challenging to understand.
     
  2. It may require additional manipulation to use with specific applications.
     
  3. It can create issues with database performance and query improvement.
     
  4. It may not be suitable with specific database management systems.
     
  5. It can make queries more challenging to write and understand.

Difference Between Single-Valued & Multivalued Attributes

Here are some critical differences between single-valued and multivalued attributes. 

Single-Valued AttributesMultivalued Attributes

Contain only one value for each entity instance.

 

It can contain multiple values for each entity instance.

 

It cannot be null.

 

It can be null in some cases.

 

It can be used as a primary or foreign key.

 

It cannot be used as primary or foreign keys.

 

Have only one value stored in a single cell of a table.

 

Require a separate table to represent the multivalued attribute relationships.

 

They are simple to query and filter.

 

Require special handling in queries and filtering.

 

It can be used for sorting data.

 

It can be helpful in simplifying data for faster queries.

 

It cannot contain repeating values.

 

It can contain repeating values.

 

Must Recommended Topic, Schema in DBMS

Frequently Asked Questions

What is multi valued attribute in relational schema?

In a relational schema, a multi-valued attribute can hold multiple values for a single entity. Unlike regular attributes, which hold a single piece of data, multi-valued attributes can store arrays or sets of values. To handle such attributes, additional tables are used to prevent data redundancy.

How are multivalued attributes represented in an ER model?

A multivalued attribute can have more than one value for a single instance of an entity. Multivalued attributes are represented in an ER model by using double ovals as the symbol.

Can a multivalued attribute be a primary or foreign key in a database?

Yes, a multivalued attribute can sometimes be a primary or foreign key in a database. However, this requires creating additional tables to manage the relationship properly.

How do you handle duplicate values in a multivalued attribute?

To avoid repeated values in a list, you can make sure they don't get added in the first place. You can also store them in a different location.

How do multivalued attributes relate to weak entities?

A weak entity do not  have a unique primary key. Multivalued attributes can indicate a weak entity. They may need a separate table to represent the data correctly. 

Conclusion

This article provided much information about Multivalued Attributes in DBMS, including their pros, cons and how they work. Learning about the multivalued attributes will improve your understanding of how data is organized using a database management system. If you want to learn more about this topic, we recommend exploring the articles below. 

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