ER/UML

Entities as boxes with their fields listed inside, and each connection marked with how many of one attach to how many of another. The counts are the point. One account has many transactions, and each transaction sits in exactly one category. Writing those counts down is usually where you discover that your categories cannot hold what you have been trying to put in them.

Entities as boxes with their fields listed inside, and each connection marked with how many of one attach to how many of another. The counts are the point. One account has many transactions, and each transaction sits in exactly one category. Writing those counts down is usually where you discover that your categories cannot hold what you have been trying to put in them.

Example

Best when the parts are kinds of records or kinds of things, and the counts between them are what you keep getting wrong.