Describe the relationship between COURSE and Enrolls

Question

BlackTom AI · Accepted Answer

The label m (5,25) on the Enrolls side of the relationship is the key indicator: it denotes the multiplicity (cardinality) of Enrolls per Course — minimum 5 and maximum 25.

1) Relevant knowledge points and concepts
- Entity-Relationship (ER) cardinality/multiplicity shows how many instances of one entity may relate to instances of another.  
- Notation "m (min,max)" next to a relationship means for each instance of the opposite entity there must be at least min and at most max related instances.  
- A label "1 (1,1)" on the Course side indicates each Enrolls instance is associated with exactly one Course (mandatory, single).

2) Step-by-step reasoning
- Inspect the connection between COURSE and the Enrolls diamond: on the COURSE side the marker reads 1 (1,1) meaning an Enrolls record links to exactly one Course.  
- On the Enrolls side (the marker adjacent to the Enrolls diamond facing COURSE) the marker reads m (5,25). That specifies for each Course there are m Enrolls, with minimum = 5 and maximum = 25.  
- Therefore, each single Course must be associated with at least 5 Enrolls and at most 25 Enrolls.

3) Intermediate steps / interpretation shown
- Read "m (5,25)" as: min = 5, max = 25 enrollments per course.  
- The "1 (1,1)" on Course confirms enrollments cannot be shared among multiple courses; each Enrolls row points to one Course.

4) Why the correct answer is correct
- The option "1 Course is associated with 5 to 25 Enrolls" directly restates the m (5,25) multiplicity for Enrolls per Course, so it exactly matches the diagram’s constraints.

5) Why other options are incorrect (briefly)
- "1 and only 1 Enrolls" contradicts the min 5 requirement.  
- "0 to 1", "1 to 25", "0 to 25" disagree with the stated minimum of 5.  
- Options saying "25 Enrolls" or "0 Course is associated..." or "5 Courses are associated..." misread which side the range applies to.  
- "No relationship" is false because a relationship diamond is present.

6) Conclusion
The correct interpretation is that one Course is associated with 5 to 25 Enrolls, confirming the provided answer.

Describe the relationship between COURSE and Enrolls单项选择题

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