Az Erdе‘rе‘l -

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

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

: A high-level view showing major entities and their relationships without technical details. AZ erdЕ‘rЕ‘l

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

: Represented as ovals, these describe the specific characteristics of an entity (e.g., a Customer entity might have attributes like Name or Email ). : The most detailed version, showing actual table

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

: Adds more detail, defining attributes and keys but remaining independent of a specific database technology. : They serve as high-level documentation of a

: Defines the numerical relationship between entities, such as one-to-one , one-to-many , or many-to-many . Why ERDs are Useful