An entity represents a real-world object, while an attribute is a characteristic, feature or property of an entity.
Entities and attributes are two of the most important concepts in database design. They can also be confusing for people who are new to databases.
In this article, we will discuss the difference between entity and attribute, and we will provide some examples to help you understand these concepts better.
Entity in Database
The entity in a database is an object, concept, or thing that can be identified and described. Entities can be anything from people to products to places. Each entity is typically represented by a table with a unique name in a relational database.
Each table in a database contains information about a specific entity. The table’s columns represent the attributes of that entity, while the rows contain the actual data values. In order to uniquely identify an entity, each table must have at least one column that is not null (i.e., has a value).
Entities can be a person, an organization, a product, a place, or something else that exists in the world. For example, the entity might be an individual customer in a customer database, while in a product catalog database, the entities would be products.
Attribute in Database
An attribute is a property or characteristic of an entity. In a database, attributes are the columns that store information about the entities in the database. The attribute name is typically stored in the column header, and the attribute value is stored in the column data.
As an example, the attributes of the entity “Person” are “First Name”, “Last Name”, and “Age”. Attributes can be used to identify an entity in a database table uniquely.
In our example, the attribute ” First Name” could be used to uniquely identify a person in the table. If two people have the same first name, the attribute “Last Name” would be used to uniquely recognize them.
Attributes can also be used to group entities together in a table. For example, the entity “Car” could have the following attributes: “Make”, “Model”, and “Year”. These three attributes could be used to group all of the cars in a database table.
The Difference Between Entity and Attribute in Database
Although entities and attributes in the database are closely connected, they play different roles in the database design process. Here are the key differences between entity and attribute:
- Entities are the real-world things in the database. Attributes are the characteristics of an entity. For example, a customer entity might have attributes like name, address, and phone number.
- Entities are usually nouns (e.g., customer, product, order). Attributes are usually adjectives (e.g., name, address, phone number).
- Entities can be concrete (e.g., a specific customer) or abstract (e.g., all customers in the database). Attributes are always associated with a specific entity.
- In the database design process, entities are usually first identified, and then attributes are assigned to each entity. This is because it’s easier to think of the “things” in the database first and then determine their characteristics.
- In a database table, an entity is represented by a row, and its attributes are represented by the columns.
- The primary key of an entity is always composed of the attribute values that uniquely identify that entity. A foreign key is a column in one table that references the primary key of another table. This allows data to be related between tables.
In a nutshell, the entity is a real-world object in the database while an attribute is a property or characteristic of that entity. They work together but have distinct functions in the database design process.
Thank you for reading! We hope this article has helped to clarify the difference between entities and attributes in a database. If you have any questions, please feel free to ask in the comments section below.