c# - 如何将空小数插入数据表？

Question

我正在创建一个数据表:

    public DataTable dt;
    public ReadFileIntoDataTable(string inputfile)
    {
        dt = new DataTable();
        dt.Columns.Add("Specimen_ID",typeof(string));
        dt.Columns.Add("Client_Key",typeof(int));
        dt.Columns.Add("Outcome",typeof(string));
        dt.Columns.Add("Medications",typeof(string));
        dt.Columns.Add("Date_Collected",typeof(DateTime));
        dt.Columns.Add("Time_Collected",typeof(DateTime));
        dt.Columns.Add("Date_Entered",typeof(DateTime));
        dt.Columns.Add("Time_Entered",typeof(DateTime));
        dt.Columns.Add("Date_Completed",typeof(DateTime));
        dt.Columns.Add("Time_Completed",typeof(DateTime));
        dt.Columns.Add("Test_Date",typeof(DateTime));
        dt.Columns.Add("Test_Time",typeof(DateTime));
        dt.Columns.Add("Practice_Name",typeof(string));
        dt.Columns.Add("Practice_Code",typeof(string));
        dt.Columns.Add("Client_ID",typeof(string));
        dt.Columns.Add("Requesting_Physician",typeof(string));
        dt.Columns.Add("Other_Medications",typeof(string));
        dt.Columns.Add("Order_Comments",typeof(string));
        dt.Columns.Add("Reference_Number",typeof(string));
        dt.Columns.Add("Order_Count",typeof(int));
        dt.Columns.Add("_6_MAM_HEROIN_METABOLITE",typeof(decimal));
        dt.Columns.Add("_6_MAM_N_HEROIN_METABOLITE",typeof(decimal));
        dt.Columns.Add("_6_MAM_S_HEROIN_METABOLITE",typeof(decimal));
        dt.Columns.Add("_6_MAM_SN_HEROIN_METABOLITE",typeof(decimal));
        dt.Columns.Add("_6_MAM_SP_HEROIN_METABOLITE",typeof(decimal));
...
..
..

            string Specimen_ID;
            string Client_Key;
            string Outcome;
            string Medications;
            string Date_Collected;
            string Time_Collected;
            string Date_Entered;
            string Time_Entered;
            string Date_Completed;
            string Time_Completed;
            string Test_Date;
            string Test_Time;
            string Practice_Name;
            string Practice_Code;
            string Client_ID;
            string Requesting_Physician;
            string Other_Medications;
            string Order_Comments;
            string Reference_Number;
            string Order_Count;
            string _6_MAM_HEROIN_METABOLITE;
            string _6_MAM_N_HEROIN_METABOLITE;
            string _6_MAM_S_HEROIN_METABOLITE;
            string _6_MAM_SN_HEROIN_METABOLITE;
            string _6_MAM_SP_HEROIN_METABOLITE;
            string _6ACE_C_6_MAM__Heroin_metabolite;

.....
........
.....
            using (GenericParser parser = new GenericParser())
            {
                parser.SetDataSource(inputfile);

                char[] delimiters = new char[] { ',' };
                parser.ColumnDelimiter = delimiters[0];
                parser.FirstRowHasHeader = true;
                //parser.SkipDataRows = 10;
                parser.MaxBufferSize = 4096;
                parser.MaxRows = 500;
                parser.TextQualifier = '\"';


                while (parser.Read())
                {
                    Specimen_ID = parser["Specimen ID"];
                    Client_Key = parser["Client Key"];
                    Outcome = parser["Outcome"];
                    Medications = parser["Medications"];
                    Date_Collected = parser["Date Collected"];
                    Time_Collected = parser["Time Collected"];
                    Date_Entered = parser["Date Entered"];
                    Time_Entered = parser["Time Entered"];
                    Date_Completed = parser["Date Completed"];
                    Time_Completed = parser["Time Completed"];
                    Test_Date = parser["Test Date"];
                    Test_Time = parser["Test Time"];
                    Practice_Name = parser["Practice Name"];
                    Practice_Code = parser["Practice Code"];
                    Client_ID = parser["Client ID"];
                    Requesting_Physician = parser["Requesting Physician"];
                    Other_Medications = parser["Other Medications"];
                    Order_Comments = parser["Order Comments"];
                    Reference_Number = parser["Reference Number"];
                    Order_Count = parser["Order Count"];
                    _6_MAM_HEROIN_METABOLITE = parser["6-MAM-HEROIN METABOLITE"];

                    _6_MAM_N_HEROIN_METABOLITE = parser["6-MAM_N-HEROIN METABOLITE"];
                    _6_MAM_S_HEROIN_METABOLITE = parser["6-MAM_S-HEROIN METABOLITE"];
                    _6_MAM_SN_HEROIN_METABOLITE = parser["6-MAM_SN-HEROIN METABOLITE"];
                    _6_MAM_SP_HEROIN_METABOLITE = parser["6-MAM_SP-HEROIN METABOLITE"];
                    _6ACE_C_6_MAM__Heroin_metabolite = parser["6ACE_C-6-MAM (Heroin metabolite)"];

.....
......
.......

                    DataRow newRow = dt.NewRow();
                    newRow["Specimen_ID"] = Specimen_ID;
                    newRow["Client_Key"] = Client_Key;
                    newRow["Outcome"] = Outcome;
                    newRow["Medications"] = Medications;
                    newRow["Date_Collected"] = Date_Collected;
                    newRow["Time_Collected"] = Time_Collected;
                    newRow["Date_Entered"] = Date_Entered;
                    newRow["Time_Entered"] = Time_Entered;
                    newRow["Date_Completed"] = Date_Completed;
                    newRow["Time_Completed"] = Time_Completed;
                    newRow["Test_Date"] = Test_Date;
                    newRow["Test_Time"] = Test_Time;
                    newRow["Practice_Name"] = Practice_Name;
                    newRow["Practice_Code"] = Practice_Code;
                    newRow["Client_ID"] = Client_ID;
                    newRow["Requesting_Physician"] = Requesting_Physician;
                    newRow["Other_Medications"] = Other_Medications;
                    newRow["Order_Comments"] = Order_Comments;
                    newRow["Reference_Number"] = Reference_Number;
                    newRow["Order_Count"] = Order_Count;
                    newRow["_6_MAM_HEROIN_METABOLITE"] = ????
                    newRow["_6_MAM_N_HEROIN_METABOLITE"] = _6_MAM_N_HEROIN_METABOLITE;
                    newRow["_6_MAM_S_HEROIN_METABOLITE"] = _6_MAM_S_HEROIN_METABOLITE;
                    newRow["_6_MAM_SN_HEROIN_METABOLITE"] = _6_MAM_SN_HEROIN_METABOLITE;
                    newRow["_6_MAM_SP_HEROIN_METABOLITE"] = _6_MAM_SP_HEROIN_METABOLITE;


.........
........
......

如您所见，我正在执行以下操作:

1. 创建数据表
2. 使用 genericparser 解析文件
3. 从文件中插入数据到数据表

我的问题是文件没有 DECIMAL 类型字段的值。我收到以下错误:

System.ArgumentException: Input string was not in a correct format.Couldn't store <> in _6_MAM_HEROIN_METABOLITE Column.  Expected type is Decimal. ---> System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseDecimal(String value, NumberStyles options, NumberFormatInfo numfmt)
   at System.String.System.IConvertible.ToDecimal(IFormatProvider provider)
   at System.Data.Common.DecimalStorage.Set(Int32 record, Object value)
   at System.Data.DataColumn.set_Item(Int32 record, Object value)
   --- End of inner exception stack trace ---
   at System.Data.DataColumn.set_Item(Int32 record, Object value)
   at System.Data.DataRow.set_Item(DataColumn column, Object value)
   at CreateTableScript.ReadFileIntoDataTable..ctor(String inputfile) in C:\Users\agordon\Documents\Visual Studio 2008\Projects\SubversionRepository\Internal Application\SalesDWH\CreateTableScript\CreateTableScript\ReadFileIntoDataTable.cs:line 930
   at CreateTableScript.Form1.button1_Click(Object sender, EventArgs e) in C:\Users\agordon\Documents\Visual Studio 2008\Projects\SubversionRepository\Internal Application\SalesDWH\CreateTableScript\CreateTableScript\Form1.cs:line 33

Answer 1

然后根本不设置该值，将使用数据表中分配的默认值。您可以将默认值更改为 0、非零或 DbNull.Value