[thelist] Newbie - DB Design Help
Ken Moore
psm2713 at hotmail.com
Mon Jul 31 12:10:03 CDT 2006
Hi all,
This is getting beyond the original question. But for the sake of being
clear, we are not talking about right and wrong but about balancing good
style with everyday restrictions.
First, data integrity problems arise from duplicate entries of the same data
and/or improper updating of data.
>From Ken Schaefer:
>These should be stored in a separate table(s). Teachers are a separate
>entity. So are subjects. Times are an attribute of the class, so would be
>fields in the Class table.
Of course teachers, classrooms, and students all have their own tables and
would be recorded as foreign keys. The following is all that is needed to
relate students and classrooms:
TABLE Classes
- ClassID
- SubjectID (FK)
- ClassroomID (FK)
The table description that Ken Schaefer gave (below) certainly answers the
original question and then some. The schema that he gives addresses the
extra and, it appears the complicating factors that I introduced about
storing extra information.
>TABLE Classes
> - ClassID
> - SubjectID (FK)
> - ClassroomID (FK)
> - TeacherID (FK)
> - Time
>
>To make this easier to visualize, I've done up a schematic:
>http://www.adopenstatic.com/temp/drawing1.jpg
The above is good enough for any textbook.
>This is where your design is starting to break down, because you are trying
>to overload one table with too many separate entities.
This depends on the relative costs. Often times, real-world constraints
interfere with database design theory. I said before that all of this could
be assembled elsewhere. With unlimited time, money, HW, programming talent,
and management approval, that is the way to go.
Let me know if you if you are aware of such a place. I know of a very good
database programmer who would be interested :-).
Ken
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