访问2010遍历记录集并更改子表单字段（如果为空）

Question

I have a command button on a mainform that when clicked runs a loop through a field on the displayed records of a subform and changes the value of all the data in that field to match the value of a unbound combobox on the mainform. It is so that users can have the option to update several records on the subform at once. The code works fine but would be more usefull if it could be changed to only update the field if it is blank for each record. In other words I want it to check if each record has a blank for that field and then populate it based on the combo box and skip to the next record if it in not blank or null. This is what the code looks like right now. I'm not very good with access VBA and am not sure if I should use "Case" or "If" or how exactly to use it with the code below.

Private Sub comm_1_Click()
Dim rs As DAO.Recordset

Set rs = Me.Skid1.Form.RecordsetClone
With rs
    .MoveFirst
    Do While Not .EOF
        .Edit
        ![Release Code] = Me.code_updater.Value
         .Update
         .MoveNext
     Loop
 End With
 Set rs = Nothing

End Sub

I have tried this but it seemed to only update some of the blank records (very strange), I'm pretty sure its close but not quite.

Private Sub comm_1_Click()
Dim rs As DAO.Recordset
Dim fld As Field

Set rs = Me.Skid1.Form.RecordsetClone
With rs
    .MoveFirst
    Do While Not .EOF
     For Each fld In .Fields

      If IsNull(fld.Value) Then
        .Edit
        ![Release Code] = Me.code_updater.Value
        .Update
         End If
        .MoveNext
          Next

    Loop
End With
Set rs = Nothing

End Sub

Answer 1

I suspect you want

Private Sub comm_1_Click()
Dim rs As DAO.Recordset
Dim fld As Field

Set rs = Me.Skid1.Form.RecordsetClone
With rs
    .MoveFirst
    Do While Not .EOF
      ''Anything, space filled, null, ZLS
      If Trim(![Release Code] & "") = "" Then
        .Edit
        ![Release Code] = Me.code_updater.Value
        .Update
      End If
      .MoveNext
    Loop
End With
Set rs = Nothing

End Sub

I suggest you edit your table and make sure it will not accept zero-length strings by setting the Allow Zero Length property to No for text data types.

Answer 2

Does this make any difference? it checks for blank fields as well as NULL fields - yes they are two different things!

Private Sub comm_1_Click()
Dim rs As DAO.Recordset
Dim fld As Field

Set rs = Me.Skid1.Form.RecordsetClone
With rs
.MoveFirst
Do While Not .EOF
 For Each fld In .Fields

  If (IsNull(fld.Value) Or fld.Value = "")Then
    .Edit
    ![Release Code] = Me.code_updater.Value
    .Update
     End If
    .MoveNext
      Next

Loop
End With
Set rs = Nothing

End Sub