What is ERD and related terms reviwe

Every software no matter the size need to have a database. A good design database provides easy management and simplifies maintenance. The correct structure and design are crucial aspects of every database. An Entity Relationship Diagram (ERD) is a type of structure used to design a relational database. ERD contains different symbols and connectors which help visualize two major aspects, the main entity in a system scope and the inter-relationships between these entities (Visual-paradigm, 2022). ER Diagrams are used in fields like software engineering, education, business, or research for designing or debugging databases (Lucidchart, 2022).

Entities, relationships, and attributes are creating the ER Diagrams, which also depict cardinality which defines the relationship in the diagram. We can clarify the main components of the Entity Relationship Diagram (Lucidchart, 2022):

Entity

A thing or concept in a system that can be defined for example person, object, event, or concept. They are a few types of entities:

• Entity type: a wide group of entities such as students of products, the main difference compared to the entity is that will concentrate on the group rather than on a specific type or a person.

• Entity set: very similar to an entity type but concentrates on a point in time such as customer purchase from the last month.

• Entity categories: Entities are defined as strong, weak, or associative. A strong entity uses its own attributes to define whereas a weak entity cannot do that. The associative entity cooperates entity with entity sets.

• Entity keys: Define the attribute in an entity set. They are a few types of keys that are defined as super, candidate, or primary (Visual-paradigm, 2022).

• Super key - A collection of attributes that define an entity in an entity set

• A candidate key - is a type of key which have a minimum set of attributes to still be classified as a super key.

• Primary key - the key that uniquely identifies the entity in a set

• Foreign key - determine the relationship between the data set

Relationship

Relationships describe how the entity works with each other or how they are connected between themselves. As an example, imagine a customer buying a car the customer will be the first entity and the car will be the second, and the purchase process will be the relation between the two that connects the two entities together. the relationship is usually shown as a diamond in the ER diagram (Lucidchart, 2022).

Attribute

An attribute is a property or characteristic describing the entity. There are several types of attributes that can be recognized: Simple: which mine that the value of the attribute is the smallest as possible and cannot be future divided, Composite: sub-attribute comes from attribute, Derived: attribute is calculated or acquired from other attributes (Lucidchart, 2022).

Cardinality

Provides numerical attributes of the relationship between entities or entity sets. The three main relationships recognized in ERD are one-to-one, one-to-many, and many-many. A good example of the relationship is (Lucidchart, 2022):

• one-to-one - A student applies for a course

• one-to-many - Curse includes many subjects

• many-many - Multiple subjects have several tutors

There are several reasons for Entity Relationship Diagram to be used. It is helping to design and model the relational database, also help to analyze database structure, or can be very handy for troubleshooting with the help of ERD, it is easier and faster to locate and fix potential problems (Lucidchart, 2022).

Reference:

Visual-paradigm, 2022. What is Entity Relationship Diagram (ERD)?. [online] Visual-paradigm.com. Available at: <https://www.visual-paradigm.com/guide/data-modeling/what-is-entity-relationship-diagram/> [Accessed 2 September 2022].

Lucidchart, 2022. What is an Entity Relationship Diagram (ERD)?. [online] Lucidchart. Available at: <https://www.lucidchart.com/pages/er-diagrams> [Accessed 2 September 2022].