Difference Between Entity and Attribute in Database

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An entity represents a real-world object, while an attribute is a characteristic, feature or property of an entity.

Entities and attributes are crucial in database design, especially for those new to databases.

Learn about the difference between entity and attribute, with examples to help you understand these concepts better.

Entity in Database

An entity in a database is an object, concept, or thing that can be identified and described. Entities include people, products, and places. Each entity is usually represented by a table with a unique name in a relational database.

Each table in a database holds information about a specific entity. The columns show the entity’s attributes, and the rows have the actual data values. To uniquely identify an entity, each table must have at least one non-null column.

Entities can be a person, an organization, a product, or a place. In a customer database, an entity might be an individual customer. In a product catalog, entities are products.

Attribute in Database

An attribute is a property of an entity. In a database, attributes are columns that store information about entities. The attribute name is in the column header, and the attribute value is in the column data.

Example: The attributes of the entity “Person” include “First Name,” “Last Name,” and “Age.” These attributes uniquely identify an entity in a database table.

The attribute “First Name” can uniquely identify a person in the table. If two people share the same first name, the “Last Name” attribute will uniquely recognize them.

Attributes can group entities in a table. For instance, a “Car” entity might have “Make”, “Model”, and “Year” attributes, organizing all cars in a database table.

  • Attributes: Columns in a database
  • Example: “First Name”, “Last Name”
  • Group entities like “Car”

The Difference Between Entity and Attribute in Database

Entities and attributes in a database have unique roles. Here are the key differences between an entity and an 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.