Crow's foot notation이란?

What do the circles and arrows mean?

This is called crows foot notation and shows the relationships by using a 'crows foot', line or circle on either side of the line connecting the entities.

E-R 다이어그램을 만들 때 테이블 간 관계 표현 시 일일히 숫자표기하기 번거로우므로 위와 같은 방법(Crow's foot notation)을 주로 사용한다.

 

출처: https://dev.to/helenanders26/entity-relationship-diagrams-explained-by-sonic-the-hedgehog-1m68