: Adds more detail, defining attributes and keys but remaining independent of a specific database technology.
: Defines the numerical relationship between entities, such as one-to-one , one-to-many , or many-to-many . Why ERDs are Useful AZ erdЕ‘rЕ‘l
: Represented as rectangles, these are the "nouns" of the system, such as Customer , Order , or Product . : 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