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Field.AllowZeroLength Property

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Access Developer Reference

Sets or returns a value that indicates whether a zero-length string ("") is a valid setting for the Value property of the Field object with a Text or Memo data type (Microsoft Access workspaces only).

Syntax

expression.AllowZeroLength

expression   A variable that represents a Field object.

Remarks

For an object not yet appended to the Fields collection, this property is read/write.

Once appended to a Fields collection, the availability of the AllowZeroLength property depends on the object that contains the Fields collection, as shown in the following table.

If the Fields collection belongs to an Then AllowZeroLength is

Index object

Not supported

QueryDef object

Read-only

Recordset object

Read-only

Relation object

Not supported

TableDef object

Read/write

You can use this property along with the Required, ValidateOnSet, or ValidationRule property to validate a value in a field.

Example

In this example, the AllowZeroLength property allows the user to set the value of a Field to an empty string. In this situation, the user can distinguish between a record where data is not known and a record where the data does not apply.

Visual Basic for Applications 
  Sub AllowZeroLengthX()

Dim dbsNorthwind As Database
Dim tdfEmployees As TableDef
Dim fldTemp As Field
Dim rstEmployees As Recordset
Dim strMessage As String
Dim strInput As String


Set dbsNorthwind = OpenDatabase("Northwind.mdb")
Set tdfEmployees = dbsNorthwind.TableDefs("Employees")
' Create a new Field object and append it to the Fields
' collection of the Employees table.
Set fldTemp = tdfEmployees.CreateField("FaxPhone", _
dbText, 24)
fldTemp.AllowZeroLength = True
tdfEmployees.Fields.Append fldTemp


Set rstEmployees = _
dbsNorthwind.OpenRecordset("Employees")


With rstEmployees
' Get user input.
.Edit
strMessage = "Enter fax number for " & _
!FirstName & " " & !LastName & "." & vbCr & _
"[? - unknown, X - has no fax]"
strInput = UCase(InputBox(strMessage))
If strInput <> "" Then
Select Case strInput
Case "?"
!FaxPhone = Null
Case "X"
!FaxPhone = ""
Case Else
!FaxPhone = strInput
End Select


     .Update

     ' Print report.
     Debug.Print "Name - Fax number"
     Debug.Print !FirstName &amp; " " &amp; !LastName &amp; " - ";

     If IsNull(!FaxPhone) Then
        Debug.Print "[Unknown]"
     Else
        If !FaxPhone = "" Then
           Debug.Print "[Has no fax]"
        Else
           Debug.Print !FaxPhone
        End If
     End If

  Else
     .CancelUpdate
  End If

  .Close



End With


' Delete new field because this is a demonstration.
tdfEmployees.Fields.Delete fldTemp.Name
dbsNorthwind.Close


End Sub

See Also