Re: Foreign Keys Question

On Thu, 2008-12-11 at 13:46 -0500, tedd wrote: > At 12:29 PM -0600 12/11/08, phphelp -- kbk wrote: > >Hey tedd --- > > > >Do I understand your structure correctly that you have something like: > > > >Courses (table) > >course_id, > >subject_id, > >student1_id, > >student2_id, > >student3_id, > >student4_id, > ><etc.> > > > >Is that right? > > > >Ken > > Ken: > > That was right, but I think I've reconsidered. > > You see, Richard pointed out the error of my ways, namely: > > Student table has student data and ID -- as may records as there are students. > > Instructor table has instructor data and ID -- as may records as > there are instructors. > > Course table has course data, ID and Instructor ID and Student ID -- > but the number of records vary. > > While there will be only one record per Instructor and one pre > Student, the Course table can have up to four records for each course > depending upon actuall attendance. > > I think that makes more sense. Student attendance should be a table with rows for each student in attendance. If you want to limit the number make a check before adding another student. Don't hard code the number via fields like above or you'll find it overly ugly to add/remove students or even increase the number of allowed students. As it stands to allow 6 students you would have to add 2 more columns. With attendance controled by a table with a row for ewach attendance you would only need to update a configuration variable the determines the maximim number of allowed students in attendance. Cheers, Rob. -- http://www.interjinn.com Application and Templating Framework for PHP