Entity relationship diagrams can be used to provide a high-level representation of a [[database]]. I prefer [[dbdiagram]] for developing ERDs. [Lucid Chart](https://www.lucidchart.com/pages/) is another good option if you need more control (import shapes associated with entity relationships). Relationships are represented using **crow's foot notation**. A single line represents a cardinality of one. A crow's foot represents a carinality of many. A single line again represents mandatory participation. A circle represents voluntary participation. Alternatives to crows foot notation include **Chen's notation** and **UML notation**. Use an asterisk to represent the primary key for each table.