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Asked: 2026-06-01T18:39:13+00:00

EDIT: was a design issue my revised final ERD https://i.stack.imgur.com/xDj6i.png I am undergoing a

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EDIT: was a design issue

my revised final ERD
https://i.stack.imgur.com/xDj6i.png

I am undergoing a computing project for Alevel computing.
The project consists of a 6 tabled Microsoft access database. I am using vb.net to code the application for a student tracking system.

My ERD is below:
http://i.imgur.com/Xl0gS.png

My problem: How to insert a new compound Primary key into a existing table?
If I increment StudID and CourseID in tblContact then I need to increment them in tblStudentCourse which leads to records not pointing to the right directions..

For enforcing the relationships I am using the .relations with the dataset.

'Student - StudentCourse
    DS.Relations.Add(New DataRelation("StudStudCorRelation", DTStudents.Columns("StudID"), DTStudentCourses.Columns("StudID"), True))
    'Course - StudentCourse
    DS.Relations.Add(New DataRelation("CourStudCorRelation", DTCourses.Columns("CourseID"), DTStudentCourses.Columns("CourseID"), True))

    StudCourseCompPK(0) = DTStudentCourses.Columns("StudID")
    StudCourseCompPK(1) = DTStudentCourses.Columns("CourseID")
    StudCourseContactCompPK(0) = DTContacts.Columns("StudID")
    StudCourseContactCompPK(1) = DTContacts.Columns("CourseID")
    StudCourseStudTMACompPK(0) = DTStudentTMAS.Columns("StudID")
    StudCourseStudTMACompPK(1) = DTStudentTMAS.Columns("CourseID")
    'Enforces the relations between these 2 keys
    DS.Relations.Add(New DataRelation("CPKContact", StudCourseCompPK, StudCourseContactCompPK, True))
    DS.Relations.Add(New DataRelation("CPKStudentTMA", StudCourseCompPK, StudCourseStudTMACompPK, True))
    DS.EnforceConstraints = True

    DTStudentCourses.PrimaryKey = New DataColumn() {DTStudentCourses.Columns("StudID"), DTStudentCourses.Columns("CourseID")}

But the last line here: 

    DTStudentCourses.PrimaryKey = New DataColumn() {DTStudentCourses.Columns("StudID"), DTStudentCourses.Columns("CourseID")}

Needs to be used to retrieve the keys from tblStudentCourse which I am unsure about what todo

If anybody could take a look at this problem I would be very grateful.

Harry

Revised ERD

enter image description here

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1 Answer

  1. Editorial Team

    If I increment StudID and CourseID in tblContact then I need to
    increment them in tblStudentCourse which leads to records not pointing
    to the right directions.

    No, values increment in only one table. Anywhere else you use those incremented values, you essentially copy them.

    So tblStudent.StudID might be an integer that gets incremented by one for each new student. tblCourse.CourseID might be an integer that gets incremented by one for each course. To store data in tblStudentCourse, you copy one appropriate, existing integer from tblStudent.StudID and another appropriate, existing integer from tblCourse.CourseID.

    StudID is incremented in only one place–tblStudent. CourseID is incremented in only one place–tblCourse.

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