Does the double line in the following ER diagrams means total participation or recursive relation?
Could anyone tell me the notation difference for both?
Total Participation: Every entity in the set is involved in some association (or tuple) of the relationship.
Recursive Relationship: An entity set relating to itself.
Most commonly in recursive relationships they indicate the different types of roles an entity can have (e.g., the different ways it can participate) in a relationship by writing each role above each line.
An example of this would be in a Course table with a relational table of Prerequisites
A Course could be both the Prerequisite and the Course and you would write those on each line.
Here's another example.
Assuming your textbook follows a similar pattern, I would assume that these are in fact total participation constraints.
double line : Used to represent total participation of an entity in a relationship set.
A recursive relationship is one in which the same entity participates more than once in the relationship.
recursive relationship example : Suppose one team is assigned the task of supervising the other teams. This supervisor team makes sure that each team records its portion of the data. The supervision relationship is a recursive relationship because the same entity, a particular team, participates more than once in the relationship, as a supervisor and as a supervisee. To draw the situation, we label the two lines between team and supervision with the two possible roles
by this definitions all three above are total participation
defination of total participation constraints: the participation of an entoty set E in the eelationship R is said to be a total if every entity in E participates in at least one relationship in R.
来源：https://stackoverflow.com/questions/19781294/whats-the-difference-in-notation-for-total-participation-and-recursive-relation