So far, our examples have demonstrated the UnboundColumnFetch event using only a single unbound column. Suppose you want to have more than one?  Since the UnboundColumnFetch is fired for each unbound column of each row, only one column value may be set at a time, and each column must be identified for the value to be properly determined. The second UnboundColumnFetch argument, Col, is used to identify the column of the list for which the value is required.

Returning to the Rectangle example, the following code also displays the perimeter of the rectangle in addition to its area:

Dim ucfClone As Recordset ' Global UnboundColumnFetch clone

Dim ucfLength As Field

Dim ucfWidth As Field

 

Private Sub Form_Load()

    Data1.Refresh

    Set ucfClone = Data1.Recordset.Clone()

    Set ucfLength = ucfClone.Fields("Length")

    Set ucfWidth = ucfClone.Fields("Width")

End Sub

 

Private Sub TDBList1_UnboundColumnFetch(Bookmark As Variant, _

        ByVal Col As Integer, Value As Variant)

 

    ucfClone.Bookmark = Bookmark

 

    Select Case TDBList1.Columns(Col).Caption

        Case "Area"

            ' Calculate "Area" column of list

            Value = ucfLength * ucfWidth

        Case "Perimeter"

            ' Calculate "Perimeter" column of list

            Value = 2 * (ucfLength + ucfWidth) 

    End Select

End Sub

Please note the use of the column captions to identify the actual column for which the value is to be set. The Caption property (instead of the index number) is sometimes necessary to identify the proper column. If columns are added or removed at run time, each column's index number could change, resulting in different values of Col for the Area column. Since the caption text is much less ambiguous than the column number, code is easier to read, more reliable, and self-adjusting to column layout changes.

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