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Cartesian Join/Value List Question


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Posted

If I have multiple tables that each have records of courses in them (from different subjects) and each record has a field for the course name ("Course"), and I want to create a value list that has the names of all courses from all subjects, shouldn't a cartesian join do this? What I tried to do is below, but it doesn't work:

Admin::CourseNames x Subject1::Course

as one relationship and:

Admin::CourseNames x Subject2::Course

as another relationship and then just defined the value list to take values from Admin::CourseNames. Any ideas on what I'm doing wrong?

Posted

A Cartesian join means that all records in one table are related to all records in another table. It would mean, for instance, if you had students in one table and courses in another table, then all students would have all courses.

I doubt that's what you want. I think you need just a regular equijoin between the tables, with the value list being the course field from the second table. Don't show just the related records; show all.

Posted

Ok, my bad. I thought that i needed to use the cartesian join in order to get the values across all the records. Thank you for straightening that out for me.

I tried the equijoin relationship so that the relationships are now:

Admin::CourseNames = Subject1::Course

and:

Admin::CourseNames = Subject2::Course

and the value list is still created using Admin::CourseNames, but the value list still comes up with "<no values defined>"

Posted

You don't need a relationship. Just define a value list using values from CourseName.

Posted

But how do I populate CourseNames with the various courses from multiple databases?

-------------------------

-Kevin

Posted

Ok, let's see if i can state this clearly enough.

I have one table (Admin) that contains the field CourseNames.

Another table (Math) that contains the field Course.

Each record contains the performance of a student in a particular course (Calculus 1, Statistics, Calculus 2, etc.)

A third table (Chem) that contains the field Course.

Again, each record contains the performance of a student in a particular course (General Chem, Organic Chem, etc.)

the way the relationships are as of this moment is:

One relationship-

Admin::CourseNames = Math::Course

Second separate Relationship-

Admin::CourseNames = Chem::Course

Then, my value list uses the value from the field Admin::CourseNames.

Does that help?

---------------------------

-Kevin

Posted

Create one value list for each applicable table. Then create an unstored calculation to concatenate them all

ValueListItems( Get(FileName); "valuelist1" ) &

Posted

It would be much easier for you in the long run if you kept all courses in one table with category and subcategory fields for them.

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