C# 无法对varchar错误调用方法

我在“adapter.Fill（dtROI）”上遇到“cannotcallmethodonvarchar”错误。你能帮帮我吗？我试图用sql语句中的适配器结果填充数据表

protected void LoadData()
{
    DateTime StartDate = dpStartDate.Date;
    DateTime EndDate = dpEndDate.Date;

    string sql = string.Empty;

    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["VTC"].ConnectionString;
        conn.Open();

        sql = "select RESERVATION.MEETING_PURPOSE, RESERVATION.PROGRAM_AREA, RESERVATION.START_DATE, RESERVATION.END_DATE, " +
                     "ROI_TRACKING.ENTRY_LOCATION, ROI_TRACKING.SALARY_SAVINGS, ROI_TRACKING.TRANSPORTATION_SAVINGS, ROI_TRACKING.TOTAL_SAVINGS. " +
                     "ROI_TRACKING.TOTAL_DISTANCE, ROI_TRACKING.TOTAL_FUEL, ROI_TRACKING.TOTAL_GSA, ROI_TRACKING.TOTAL_AIRFARE, ROI_TRACKING.TOTAL_INSPECTOR_SALARY, " +
                     "ROI_TRACKING.TOTAL_MGR_SALARY, ROI_TRACKING.TOTAL_SUPERVISOR_SALARY " +
                     "from RESERVATION, ROI_TRACKING WHERE ROI_TRACKING.MEETING_ID = RESERVATION.MEETING_ID";

        using (SqlCommand cmd = new SqlCommand(sql, conn))
        {
            SqlDataAdapter adapter = new SqlDataAdapter();
            adapter.SelectCommand = cmd;

            DataTable dtROI = new DataTable();
            adapter.Fill(dtROI);
            gridReports.DataSource = dtROI;
            gridReports.DataBind();

        }

        if (chkDate.Checked == true)
        {
            FilterDataGridByDate(StartDate, EndDate);
        }
    }
}

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我注意到，在ROI\u跟踪后，您使用的是“.”而不是“，”。节省的总成本。它应该是ROI\u跟踪。总成本节约

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希望这会有所帮助。

您是否尝试将sql语句复制到Sequel Server Management Studio并从那里运行它？你得到结果了吗？