: Adds more detail, defining attributes and keys but remaining independent of a specific database technology.
: They provide a common visual language for stakeholders, business analysts, and engineers to discuss data requirements. AZ erdЕ‘rЕ‘l
: They act as a blueprint for developers to build the actual physical database. : Adds more detail, defining attributes and keys
: The most detailed version, showing actual table structures, data types, and constraints for a specific database management system. : Adds more detail
: Represented as rectangles, these are the "nouns" of the system, such as Customer , Order , or Product .
: Represented as diamonds or connecting lines, these show how entities interact (e.g., a Customer "places" an Order ).
: Analysts use them to identify logic errors in existing database structures.
