Entity-Relationship Diagram (ERD)

Entity Relationship Diagram (ERD) is a data modeling technique that graphically shows entities of information systems and the relationships between these entities. ERD is a concept and expression model for representing data of the Entity Framework infrastructure.

Entity Relationship Diagram (ERD) is essential for creating an excellent database design. It is used as an advanced logical data model for conceptual design of development database.

An entity is an independent reality project or concept. An entity corresponds to a database table in a relational database, and each row in the table represents an instance of an entity

The attributes of an entity are specific attributes that describe the entity. A relationship is an association that describes the interaction between entities. In the context of ERD, a radix is ​​the number of instances of an entity that must be associated or associated with each instance of another entity. Usually, there is a one-to-one, one-to-many, or many-to-many relationship.

For example, consider two real societies, employees and their departments. Employees have attributes such as employee number, name, department number. Likewise, you can define department number and department name as department attributes. A department can talk with many employees, but because an employee can only belong to one department, a one-to-many relationship may be defined between departments and employees.

In an actual database, the employee table uses the department number as a foreign key and is referenced from the department table to enhance the relationship.

Entity Relationship Diagram (ERD), also called Entity Relationship Model, is a graphical representation of an information system that describes relationships among people, objects, places, concepts, or events within a system. ERD is a data modeling technique that defines a business process and functions as a basis for a relational database. Entity relationship diagrams can also be used to provide a visual starting point for database design and to help determine information system requirements across the organization. Even after relational database release, if you need to redesign debugging and business processes later, you can use ERD as a reference point.

The first step in this process is to create an Entity Relationship Diagram (ERD). This ERD displays and identifies the entity and its attributes. ERD visualizes how entities interact according to relationships between entities and corporate business rules. These rules are the first step to identify the structure of the database table. Technical and important elements of database design are normalization. This is the focus of this section.

Entity relationship diagram, also called ERD, ER diagram, or ER model, is a structural diagram for database design. ERD contains a variety of symbols and connectors that visualize two important pieces of information. It is the interrelationship between the main entities in the system and these entities. Database design - Depending on the scale of the change, it is dangerous to directly change the database structure with the DBMS. Please carefully plan the changes to prevent the data in the production database from being corrupted. ERD is a useful tool. By visualizing the ER diagram and visualizing the idea of ​​database design you can identify errors and design flaws and correct them before performing database changes.