Relation Object, Relations Collection Example
This example shows how an existing Relation object can control data entry. The procedure attempts to add a record with a deliberately incorrect CategoryID; this triggers the error-handling routine.
Sub RelationX()
Dim dbsNorthwind As Database
Dim rstProducts As Recordset
Dim prpLoop As Property
Dim fldLoop As Field
Dim errLoop As Error
Set dbsNorthwind = OpenDatabase("Northwind.mdb")
Set rstProducts = dbsNorthwind.OpenRecordset("Products")
' Print a report showing all the different parts of
' the relation and where each part is stored.
With dbsNorthwind.Relations!CategoriesProducts
Debug.Print "Properties of " & .Name & " Relation"
Debug.Print " Table = " & .Table
Debug.Print " ForeignTable = " & .ForeignTable
Debug.Print "Fields of " & .Name & " Relation"
With .Fields!CategoryID
Debug.Print " " & .Name
Debug.Print " Name = " & .Name
Debug.Print " ForeignName = " & .ForeignName
End With
End With
' Attempt to add a record that violates the relation.
With rstProducts
.AddNew
!ProductName = "Trygve's Lutefisk"
!CategoryID = 10
On Error GoTo Err_Relation
.Update
On Error GoTo 0
.Close
End With
dbsNorthwind.Close
Exit Sub
Err_Relation:
' Notify user of any errors that result from
' the invalid data.
If DBEngine.Errors.Count > 0 Then
For Each errLoop In DBEngine.Errors
MsgBox "Error number: " & errLoop.Number & _
vbCr & errLoop.Description
Next errLoop
End If
Resume Next
End Sub