For Each dr As DataRow In DataTables("表A").DataRows If dr("逻辑列") = False AndAlso dr.IsNull("第一列") AndAlso dr("时间列") < Date.now Then Dim fdr As DataRow = DataTables("表A").Find("第一列 = '" & dr("第二列") & "'") If fdr Is Nothing Then dr("第一列") = dr("第二列") dr("第二列") = Nothing End If End If Next