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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?
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:
Simple Attribute: A single-valued attribute.
Composite Attribute: An attribute having multiple simple attributes.
Multivalued Attribute: An attribute with multiple values for a single entity instance.
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.
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.
Step 3: To display the contents of the Coder's table
SELECT * FROM Coders;
OUTPUT
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.
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
Pros and Cons of Multivalued Attribute
Pros of Multivalued Attribute
It avoids data duplication.
It increases data accuracy and stability.
It allows better organization of data.
It will enable easier querying and sorting of data.
It improves data recovery speed and efficiency.
Cons of Multivalued Attribute
It makes data modelling more complex and challenging to understand.
It may require additional manipulation to use with specific applications.
It can create issues with database performance and query improvement.
It may not be suitable with specific database management systems.
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 Attributes
Multivalued 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.
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.