Erdе‘rе‘l — Az

: They act as a blueprint for developers to build the actual physical database.

: They serve as high-level documentation of a system’s information architecture. Levels of Abstraction

: Adds more detail, defining attributes and keys but remaining independent of a specific database technology. AZ erdЕ‘rЕ‘l

: Represented as rectangles, these are the "nouns" of the system, such as Customer , Order , or Product .

: Defines the numerical relationship between entities, such as one-to-one , one-to-many , or many-to-many . Why ERDs are Useful : They act as a blueprint for developers

: Analysts use them to identify logic errors in existing database structures.

: They provide a common visual language for stakeholders, business analysts, and engineers to discuss data requirements. : Represented as rectangles, these are the "nouns"

: The most detailed version, showing actual table structures, data types, and constraints for a specific database management system.