ERD diagram or entity–relationship diagram is usually the result of systematic analysis to define and describe what is important to processes in an area of a business. This diagram presents a business data schema in graphical form. It is usually drawn in a graphical form as boxes (entities) that are connected by lines (relationships) which express the associations and dependencies between entities. The first example below illustrates a bookstore ER diagram.
In an ERD diagram, entities may be characterized not only by relationships, but also by additional properties (attributes), which include identifiers called “primary keys”. An ER model is typically implemented as a database. In a simple relational database implementation, each row of a table represents one instance of an entity type, and each field in a table represents an attribute type.
Also known as ERDs or ER Models, they use a defined set of symbols such as rectangles, diamonds, ovals and connecting lines to depict the interconnectedness of entities, relationships and their attributes. They mirror grammatical structure, with entities as nouns and relationships as verbs.
Entity-relationship diagrams (ERD) are essential to modeling anything from simple to complex databases, but the shapes and notations used can be very confusing. All these pictures presented are printable ERD diagrams resources. Hopefully, these examples will give you more insight about the diagram. Learn more about the other educational diagrams by browsing through our categories or looking it up on the search column!