Entities and Attributes of Database There will be three main entities in the system; the students, the instructors and the courses. The students’ attributes would be last name, first name, social security number, and phone number, date of birth, address, student ID, level of education, enrollment date, GAP any standardized test scored, all accepted credits, and their class schedule. The attributes for the instructors would be last name, first name, teacher ID, salary, address, telephone numbers (and or extensions), certifications, degrees, and the course code that they will be teaching.
The courses attributes would be a specific course code. Along with the course code each individual class would have to have a code as well. This WOUld make the system easier to keep track of instead of having it spelled out next to either the instructors’ or the student’s name. The relationship of this database would be a many-to-many relationship. This would be because each class can be taken by many different students as well as a student can take many different classes making it M: N. (Coroner pig. 5) Business Rules There are several business rules that would impact the database.
It would be up to the college but the minimum and maximum amount of courses that each teacher can teach would be an impact. The amount of students allowed in each course would be an impact. If there are too many students for one class but not enough students for two classes that would create a problem. The students would have to either prolong their time for the course or the institution would have to find more students to fill the second class. There will be many different constraints in the database. An example of a constraint is one if the students’ GAP will have to be between 0. 0 and 4. 00. Another example would be that each class can only have one instructor. There would be a constraint on the social security number ensuring that there are only nine numbers and in the format is xx-xx-xx, and each individual number would be between 0 and 9. There would be a constraint for the telephone numbers as well. Each individual number would be between O and 9 in the format of (xx)-xx-xx. Conceptual vs.. Physical Model The conceptual model will have all of the attributes from the students as well as he instructors.
It will also have the all of the constraints. This model will have software and hardware independence. At this level any changes to the database management system will not affect this model. The physical model will take all the information that comes from the conceptual model and describe it so that it can be saved and stored. This model will need to know the physical storage device and access method so that it can reach the information stored in the devices. The physical model, not like the conceptual, will be both software and hardware dependency.