Entering Data in the Associative Entity Table of a M:M or Ternary Relationship

1
Entering Data in the Associative Entity Table of
a MM or Ternary Relationship

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• This presentation was prepared by Professor Steve
  Ross, with the advice of other MIS Faculty, for
  use in MIS Classes at Western Washington
  University. Please contact Dr. Ross for
  permission to use in other settings..

2
The Database
3
Access Relationships
4
The Challenge

• Create a form for the entry of worker
  assignments, to include the foreign keys for
  WorkerID and BuildingID
• Information about both buildings and workers must
  be entered prior to use of this form

5
Creating the Form, Step 1

• Specify the table or view that the form affects
• tblAssignment or vueAssignment
• For each field in the table or view, indicate
  whether it is editable and constrained
• WorkerID editable, FK to tblWorker
• BuildingID editable, FK to tblBuilding
• StartDate editable

6
Designing for Usability Foreign Keys

• Users shouldnt have to know or remember foreign
  key values
• Instead, present them a set of choices ordered in
  a meaningful manner
• If there are only a few choices and the list
  rarely changes, radio buttons may be used
• If there are several choices and/or the list
  changes or is not known in advance, use a combo
  box based on a query

7
Creating the Form, Step 2

• Create a draft view of the form, giving
  approximate placement and type of controls for
  each data item

I usually do this by hand, not in a graphic
program such as this
Standard Form Heading
Person Building Start Date
Person list combo box
Building list combo box
StartDate
These will be combo boxes, bound to the relevant
fields but displaying data from the related tables
These will be a text box bound to the relevant
field
8
Creating the Form, Step 3

• Use the application generator to create version 1
  of the form. This one will probably have text
  boxes for the foreign keys.

9
Creating the Form, Step 4

• Convert the foreign key controls to combo
  boxes
• The combo box row source is either a named view
  (e.g., vueRankID) or a SQL statement (e.g.,
  SELECT RankID,Rank FROM tblRank)

Technique will be demonstrated in class.
10
Creating the Form, Step 5

• Apply check constraints and other properties to
  controls.
• Once controls are set, apply other design
  standards.

The form illustrated here does not necessarily
meet all MIS 421 design standards.