Rob creates a course_details table that has four columns: course _id, course_name, semester and credits. a course may have 0.5 credit if it is for 1 semester and 1 credit if it is for 2 semesters. which field should rob assign as a primary key in the table?

Course_ID should be made the primary key

Explanation:

For a field to be made a primary key, the following among other things, should hold;

1. It must be unique: It cannot contain duplicates. Every row/entry has a different value of the field. Course_ID satisfies this condition. Every course has their own different ID. Course_Name may also satisfy this condition. Every course may have their own separate name. Other fields do not satisfy this condition. One or more courses may be taken in the same semester and may also have the same credit unit.

2. It must not be null: For a field to be made a primary key, it must not contain null values. All fields satisfy this condition though.

3. It must not change over time: A field that could be changed so frequently should not be made a primary key. Among all the fields listed, only Course_ID completely satisfy this condition. Course_ID cannot be easily or frequently changed. There are higher chances that other fields change anytime.

4. Preferably numeric: Numeric fields are better used as primary key so that certain rules could be applied to automatically generate them. For example, one might create a rule that auto increments the field dynamically. Course_ID satisfies this condition.

Hope this helps!