Entity-contact model (Exercise)

2. 1: explain the differences between terms of the master code, candidate code, and supercode.

A: supercode: a set of entity attributes that identify the uniqueness of an object.

Candidate Code: The smallest hypercode set.

Master code: the candidate code selected by the Database Designer.

2. 2: design a E-R diagram for the vehicle insurance company. Each customer has one or more vehicles. Each vehicle may have zero or any number of accidents.

A:

 

2. 3: For the hospital design a E-R diagram. The hospital has many patients and many doctors. The records related to each patient are a series of examinations and tests.

A:

2. 4. the registration office of a University maintains data on the following entities: (a) courses, including numbers, names, credits, course outlines and optional conditions; (B) courses provided, including course number, year, term, number of sections, teacher, time and classroom; (c) student, including student ID, name and Plan (Program); (d) instructor, including the ID number, name, department, and title. In addition, the registration of student courses and the evaluation of the scores of each course selected by the student should be properly modeled. Construct a E-R diagram for the Registry and describe the assumptions about the ing constraints.

A:

Correction: add the score field to the stufentcourse table.

It's time to write the answer to the exercise on the blog.