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Re: Advice on SQL and records

From: David Cressey <david.cressey_at_earthlink.net>
Date: Tue, 23 Aug 2005 13:22:35 GMT
Message-ID: <vqFOe.747$9i4.137@newsread2.news.atl.earthlink.net>

"FRAN" <fran_beta_at_hotmail.com> wrote in message news:1124756544.927652.224000_at_f14g2000cwb.googlegroups.com...

> Lets say for the sake of argument, that we have a school with 500
> students (pretty close to the size of the place where I teach
> actually).
>

So there will be about 500 rows in the student table.

> In this hypothetical school, students take a minimum of five courses
> and a maximum of 8 courses. In total, there are 40 different courses at
> the school.

So there will be 40 rows in the courses table.

And from 2500 to 4000 rows in the StudentCourses table. 500* 5 up to 500*8

>
> Each course is listed in the StudentCourses table. Each course name is
> the value of the CourseID field. A foreign key from the Students table
> called "StudentID" uniquely identifies each student in each course.
>
> All 500 students are listed in the "Students" table. This table has
> "CourseID" as a foreign key.
>
> The aggregate number of instances of a StudentID (regardless of
> duplicates) appears in all the courses for which there are records is
> 3860.
>
> Is it likely that the number of records in StudentCourses is
>
> a) 40
> b) 3860
> c) 40*500 (ie 20000)
> d) Something else worked out by another method
> e) Insufficient data to determine an ballpark answer
>
>
> Assuming it's not (a) I'd like the reasoning so I can get it clear in
> my head.
>

I guess it's (b) Received on Tue Aug 23 2005 - 08:22:35 CDT

Original text of this message

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