Entity expression

An entity declaration consists of the keyword "entity" followed by its name, the entity it inherits from (if any), and a list of its attributes. The following example declares an entity with the name "Dog" which has the attributes "name", "breed", "age" and the key attribute "d_id".

entity Dog {
  d_id key
  name
  breed
  age
} 

Entity attributes

An entity attribute may be declared as a key attribute by adding the keyword key after the attribute name. Also, the ERdoc language allows attributes to be composite following the attribute: [part1, part2, partN] syntax. The following example shows an entity with a composite attribute that is also part of the key of the entity.

entity Company_Branch {
  company_name key
  address: [street, city, zip] key
  revenue
}