title: Do we consider total/partial participation for the whole lifetime of the database in entity relationship diagram?
body: <p>Do we consider total/partial participation for the whole lifetime of the database in entity relationship diagram?</p>
  
  <p>I mean sometimes during a certain time of the database the participation between an entity type and the relationship could not be hold but it normally does exist</p>
  
  <p>For example, a relationship between course and section at the university. The participation of section is total for sure. But what about the course? Usually when a major is specified, the courses of the major are specified and exist in the database but at a certain time the course do not have any sections, which is the case before students register to the major or between semesters, at the vacation time ...etc. In this case do we consider it partial? Because it is partial at a certain time but while the semester holds it is total.</p>