Question

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;
}

如您所见，此代码使用Linq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

挂断似乎是＆＃39;％Down＆＃39;行未正确投射。它在SQL中是一个十进制类型，因此有意义的是它可以在C＃中输入int类型。不幸的是，当我运行程序时，我收到了一个＆＃34; InvalidCastException＆＃34;信息。请注意，如果我注释掉以下C＃片段：

＆＃34; AvgPercDown = grp.Average（r =＆gt; r.Field（＆＃34;％Down＆＃34;）），＆＃34;和＆＃34; grp.AvgPercDown，＆＃34;

代码＆＃34;工作＆＃34;。当然，这不是解决办法。 /耸肩

有什么想法？我怎样才能解决这个问题？我已经尝试过投射'％Down'＆＃39; row（在C＃代码中）作为int以外的东西（例如double），但它不是那样的。

Answer 1

实际上，根据我的经验，Oracle decimal没有正确转换为C＃Int，使用OracleDataReaders时我必须将值作为小数并将其转换为Int。一些较新版本的ODAC似乎纠正了这个问题的部分内容。

Answer 2

看起来像＆＃34;％Down＆＃34;是十进制值。在这种情况下，您应该使用：

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

InvalidCastException由DB行引起的错误？

2 个答案: