Define and state in precise terms the cardinality and partic

Define and state in precise terms the cardinality and participation in Figure 8.6, the STUDENT/COURSE/INSTRUCTOR/BUILDING database. Discuss the structural constraints of Figure 8.6. What are the participations, what are the cardinalities, and Under which circumstances would the ones depicted be correct or incorrect?

Figure 8.6 number Lives maintenance time Supervisor occupancy Buildin class sq. ft. room numbe office office hours student name M Student enroll IM K teach terminal institution Instructor major student ID book course name nstructor ID instructor

Solution

Participation (or) Optionality Constraints-

Participation concerns with the involvement of entities in a relationship. It specifies whether the existence of an entity depends on another entity. There are two types of Participation Constraints -

Cardinality/Mapping Cardinality-

Cardinality expresses the number of entities to which another entity can be associated via a relationship set (or) It specifies the number of relationship instances that an entity can participate in a relation set. There are 4 types of Cardinality Ratios :

Take the STUDENT–COURSE relationship,its a M:N relationship . This relationship is M:N because students take many courses and courses are taken by many students.The student relation fully participates in the relationship and the course relation also fully participates in the relationship.Every student have to be enrolled in a course and every course is enrolled with a student.

Take the COURSE-INSTRUCTOR relationship.The relationship between INSTRUCTOR and COURSE is teach — instructors teach many courses, a course is taught by an instructor.

An instructor may teach many(one or more) courses  Some instructors may not teach courses -- partial participation.

Courses are taught by an instructor. No course is taught by more than one instructor -- full participation

Next we take the building entity. A student lives in a building,the instructors offices are in a building and the courses are taught inside a building.

Now take STUDENT-BUILDING relationship. Many students lives in many buildings and in a building many students live.So its a M:N relationship.

All students lives in a building--full participation.

A building may contain one or more students. There are some buildings where students never live --- partial participation.

Now take COURSE-BUILDING relationship. In a building,many classrooms are there and a classroom is located in only one building. So COURSE-BUILDING relationship is a 1:M relationship.

All courses are taught in a classroom and all classrooms are in a building -- full participation

A building may contain one or more classrooms. There are some buildings which has no classrooms --- partial participation.

Now take INSTRUCTOR-BUILDING relationship. In a building,many offices are there and a office is located in only one building. So INSTRUCTOR-BUILDING relationship is a 1:M relationship.

All offices are in a building -- full participation

A building may contain one or more offices. There are some buildings which has no office --- partial participation.