Multiple object pointer fields

[Ruslan Zasukhin]

On 9/16/05 7:42 PM, "Chris Sheffield" <cmsheffield at gmail.com> wrote:

Hi Chris,

> So as a follow up to this, I've now created a new table called
> TeachStuInt.  It contains ObjectPtr fields TeacherPtr, ClassPtr, and
> StudentPtr. Is it bad to have three object pointer fields like this?

NO, this is normal practice for Relational model.
This table play role of link that links 3 tables.

>  Would it be better to create two separate tables, one for
> Teachers and Students and one for Classes and Students?  I'm not sure
> if any of this even makes sense to you guys.

But this depend on your task!

3-link is not the same as 3 links between each pair.

 
> Anyway, with my new table I still can't seem to get the query right,
> and maybe it's just because I'm not sure how the SQL should be for
> Valentina.  I keep getting a 616 wrong expression error.  This is
> just a simple test query that I'm running using ViSQL:
> 
> SELECT Teachers.LastName, Classes.ClassName, Students.LastName FROM
> Teachers, Classes, Students WHERE
> Students.RecID=TeachStuInt.StudentPtr AND
> TeachStuInt.TeacherPtr=Teachers.RecID
> 
> Why does this give me the 616 error?  Can anyone help?  What is
> proper syntax for a query dealing with a many-to-many relationship?

-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

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