InvalidCastException Error caused by DB row?

我有以下c#代码:

private DataSet GetSummaryData(DataSet ds)
{
    DataSet dsSum = new DataSet();
    DataTable dtSum = new DataTable();

    DataTable dataTable = ds.Tables[0];
    if (dataTable != null)
    {
        if (dataTable.Rows.Count > 0)
        {
            if (dataTable.Columns.Count > 1)
            {
                dtSum.Columns.Add("Line Number", typeof(int));
                dtSum.Columns.Add("Throughput", typeof(int));
                dtSum.Columns.Add("Lost Time", typeof(int));
                dtSum.Columns.Add("Pounds Made", typeof(int));
                dtSum.Columns.Add("Pounds Lost", typeof(int));
                dtSum.Columns.Add("Yearly Potential", typeof(int));
                //Getting the Subtotal of PoundsMade based on the Line Number column
                //C# linq query
                var query = from row in dataTable.AsEnumerable()
                            group row by row.Field<int>("Linenumber") into grp
                            orderby grp.Key
                            select new
                            {
                                Linenumber = grp.Key,
                                TotalPoundsMade = grp.Sum(r => r.Field<int>("Pounds Made")),
                                AvgThroughput = grp.Average(r => r.Field<int>("Throughput")),
                                TotalLostTime = grp.Sum(r => r.Field<int>("Lost Time")),
                                AvgPercDown = grp.Average(r => r.Field<int>("% Down")),
                                TotalPoundsLost = grp.Sum(r => r.Field<int>("Pounds Lost")),
                                TotalYearlyPotential = grp.Sum(r => r.Field<int>("Yearly Potential")),
                            };
                foreach (var grp in query)
                {
                    dtSum.Rows.Add(grp.Linenumber, grp.TotalPoundsMade,grp.AvgThroughput,grp.TotalLostTime, 
                        grp.AvgPercDown, grp.TotalPoundsLost, grp.TotalYearlyPotential);
                    string strXML = null;
                        strXML = strXML + "<set name='" + grp.Linenumber + "' value='" + grp.TotalPoundsMade + "'/>";
                }
            }
        }
    }
    dsSum.Tables.Add(dtSum);
    return dsSum;
}

如你所见，这段代码使用Linq来访问我的数据库。SQL是:

SELECT 
    PDT.LineNumber, 
    SUM(prdt.PoundsMade) as 'Pounds Made',
    CAST(ROUND(SUM(CAST(prdt.PoundsMade as DECIMAL))/ (MIN(LSA.AvailableHRS) - SUM(PDT.DownTimeHrs)),0,0) as int) 
as 'Throughput',
    SUM(PDT.DownTimeHrs) as 'Lost Time',
    Str(ROUND(CAST(SUM(PDT.DownTimeHrs) as DECIMAL)/CAST(MIN(LSA.AvailableHRS) as DECIMAL) * 100,0), 3,0) + '%' 
as '% Down', 
    CAST((ROUND(SUM(CAST(prdt.PoundsMade as DECIMAL))/ (MIN(LSA.AvailableHRS) - SUM(PDT.DownTimeHrs)),0,0))  * 
(SUM(PDT.DownTimeHrs)) as int) as 'Pounds Lost',
    CAST(ROUND(SUM(CAST(prdt.PoundsMade as DECIMAL))/ (MIN(LSA.AvailableHRS) - SUM(PDT.DownTimeHrs)),0,0) as int) * 
24 * 365  as 'Yearly Potential' 
FROM  
    rpt_Line_Shift_ProdDownTime AS PDT
    LEFT OUTER JOIN rpt_Line_Shift_Prod AS Prdt  
    ON  PDT.LineNumber = Prdt.LineNumber
    and PDT.ShiftNumber = Prdt.ShiftNumber 
    and PDT.WorkDate = Prdt.WorkDate 
    INNER JOIN rpt_Line_Shift_AvailableHrs AS LSA
    ON  PDT.LineNumber = LSA.LineNumber 
    and PDT.ShiftNumber = LSA.ShiftNumber
WHERE 
    PDT.WorkDate BETWEEN @p_From_Date and @p_Through_Date 
GROUP BY  
    PDT.LineNumber, PDT.ShiftNumber 
ORDER BY 
    PDT.LineNumber, PDT.ShiftNumber 

挂起似乎是'% Down'行没有正确铸造。它在SQL中是十进制类型，因此在c#中可以转换为int类型是有意义的。不幸的是，当我运行程序时，我收到一个"InvalidCastException"消息。注意，如果我注释掉下面的c#代码片段:

"AvgPercDown = grp。平均(r => r. field ("% Down"))，"answers"grp。AvgPercDown。"

代码"有效"。当然，这不是解决办法。/耸耸肩

任何想法吗?我该如何解决这个问题?我试过将'% Down'行(在c#代码中)转换为int(如double)以外的东西，但它不喜欢那样。

AvgPercDown = grp.Average(r => r.Field<decimal>("% Down")),