没人接招，谢谢老朱的提示，搞定了，分享一下。

If _CheckError=False Then Return  \'不需检测错误则退出
\'测检数据合法性
Dim r As Row = Tables(e.DataTable.name).current
If r Is Nothing Then Return
Dim cols() As String={"请购单别","请购单号","请购部门","请购日期"}
For Each col As String In cols
    If  r.IsNull(col) = True  Then
        If Forms("请购单").Opened Then
            For Each c As WinForm.Control In Forms("请购单").Controls
                Dim t As WinForm.Control  = c
                If c.BindingField  > ""  Then
                    If c.BindingField.Contains(col)=True Then
                        c.Error="[" & col & "]" & "不允许为空!"
                        _HasError=True
                    End If
                End If
            Next
        End If
    Else
        _HasError=False
        Forms("请购单").ClearErrors
    End If
Next