If e.DataCol.Name = "日期" Then
      For Each dr As DataRow In e.DataTable.Select("[_SortKey] >= " & e.DataRow("_SortKey"))
            Dim Val1 As Double = e.DataTable.Compute("Sum(借方金额)","[_SortKey] <= " & dr("_SortKey"))
            Dim Val2 As Double = e.DataTable.Compute("Sum(贷方金额)","[_SortKey] <= " & dr("_SortKey"))
            dr("余额") = Val1 - Val2
        Next

End If

按钮的代码为：

If MainTable.Name = "金额明细帐" Then
    Dim f As New Filler
    DataTables("金额明细帐").DataRows.Clear() \'清除原有数据
    f.SourceTable = DataTables("凭证库")
    f.SourceCols = "日期,凭证号,摘要,借方数量,借方金额,贷方数量,贷方金额"
    f.DataTable = DataTables("金额明细帐")
    f.DataCols = "日期,凭证号,摘要,借方数量,借方金额,贷方数量,贷方金额"
    f.Filter = ("[子目] = \'"& vars("dwmc") & "\'")
    f.Fill()
End If
If MainTable.Name = "金额明细帐" Then
    DataTables("金额明细帐").DataCols("借方数量").RaiseDataColChanged()
End If
With DataTables("金额明细帐")
    .DataCols("日期").RaiseDataColChanged(.DataRows(0))
End With