A type of entity-relationship model is the Entity-Relationship model (ER model). It’s a high-level data model. In addition, This model describes the data pieces and relationships for a specific system.
After that, It creates the conceptual architecture of a database. It also generates a data view that is incredibly convenient and simple to construct.
In other words, In ER modelling, the database structure is represented by an entity-relationship diagram.
Example of ER Model
For instance, Let’s say we’re creating a database for a school. The student will be an object in this database, with attributes such as address, name, id, age, and so on. There will be a relationship between the address and another entity with attributes such as city, street name, pin code, and so on.
Entity
The object, location, person, or event that stores data in the database may be an entity. Furthermore, In an object-relationship diagram, a rectangle represents an entity.
Entity type:
A list or a set of entities having certain common attributes is an entity type. That is to say, In a database, a name and a list of attributes define each type of entity.
Entity set:
It is a set (or collection) of entities of the same kind that share attributes or related properties.
Attribute
In an Entity-Relationship Model, an attribute defines an entity’s properties or characteristics. Additionally, It is represent in the ER diagram by an oval or ellipse shape. Each oval shape represents one attribute and is directly linked to the person that is in the shape of the rectangle.
There are four types of attributes:
1. Key attribute
2. Composite attribute
3. Multivalued attribute
4. Derived attribute
Relationship
Therefore, In the Entity-Relation Model, a relationship is used to define the relationship between two or more entities. Moreover, In the ER diagram, it is illustrated by a diamond shape.
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