datagridview绑定datatable数据，添加合计行，后可排序

F:\Test\table\DataGridViewSumRow\bin\Release\DataGridViewSumRow.exe F:\Test\table\DataGridViewSumRow\bin\Release\DataGridViewSumRow.pdb F:\Test\table\DataGridViewSumRow\obj\Release\ResolveAssemblyReference.cache F:\Test\table\DataGridViewSumRow\obj\Release\DataGridViewSumRow.Form1.resources F:\Test\table\DataGridViewSumRow\obj\Release\DataGridViewSumRow.Properties.Resources.resources F:\Test\table\DataGridViewSumRow\obj\Release\DataGridViewSumRow.csproj.GenerateResource.Cache F:\Test\table\DataGridViewSumRow\obj\Release\DataGridViewSumRow.exe F:\Test\table\DataGridViewSumRow\obj\Release\DataGridViewSumRow.pdb