Database Design for Time Table Generation

Question

I am doing a project using J2EE(servlet) for Time Table Generation of College. There are Six Slots(6 Hours) in a Day

    4 x 1 HR Lectures
    1 x 2 HR Lab

There Are three batches ( 3IT, 5IT, 7IT)

   2 Classroom 
   1 LAB

Each slot in the time table will have

       (Subject,Faculty)

For Lab I will duplicate the slot. The Tables

    Subject(SubjectID  INT, SubjectName VARCHAR);
    Faculty(FacultyID INT,FacultyName VARCHAR,NumOfSub INT,Subjects  XYZ);

Here I am not able to decide the DATATYPE for subject. What should I do ? Since a faculty can teach multiple subjects ? Also how to link with Subject Table ?

PS Using MySQL Database

Answer 1

You don't want to actually store either NumOfSub (number of subjects) OR Subjects in Faculty . Storing subjects that way is a violation of First Normal Form , and dealing with it would cause major headaches.
Instead, what you want is another table:

FacultySubject
----------------
FacultyId  -- fk for Faculty.FacultyId
SubjectId  -- fk for Subject.SubjectId

From this, you can easily get the count of subjects, or a set of rows listing the subjects (I believe MySQL also has functions to return a list of values, but I have no experience with those):
This query will retrieve the count of Subjects taught by a particular teacher:

SELECT Faculty.FacultyId, COUNT(*)
FROM Faculty
JOIN FacultySubject
  ON FacultySubject.FacultyId = FacultyId.FacultyId
WHERE Faculty.FacultyName = 'Really Cool Professor'
GROUP BY Faculty.FacultyId

... and this query will get all the subjects (named) that they teach:

SELECT Subject.SubjectId, Subject.SubjectName
FROM Faculty
JOIN FacultySubject
  ON FacultySubject.FacultyId = FacultyId.FacultyId
JOIN Subject
  ON Subject.SubjectId = FacultySubject.SubjectId
WHERE Faculty.FacultyName = 'Really Cool Professor'

(note that this last returns the subjects as a set of rows ie:

SubjectId    SubjectName
=========================
1            Tree Houses
2            Annoying Younger Sisters
3            Swimming Holes
4            Fishing

)