在列中执行计算 SUM() 时出错

Question

我已经尝试计算我的数据网格中的一列，我将按照下面的代码在我的代码中显示这些列。我不断收到这些错误。

我浏览了这些链接
1. How To Convert The DataTable Column type?
2. Error while taking SUM() of column in datatable
3.Invalid usage of aggregate function Sum() and Type: String

//This is the column i add into my datagrid
MITTRA.Columns.Add("Min_Tol");
MITTRA.Columns.Add("Max_Tol");
MITTRA.Columns.Add("Min_Weight");
MITTRA.Columns.Add("Max_Weight");

// The following codes is working finely
// if you notice MTTRQT column, it's a data queried from database
for (int i = 0; i <= MITTRA.Rows.Count - 1; i++)
{
    string item = MITTRA.Rows[i]["MTITNO"].ToString();

    Tolerancechecking = database_select4.LoadUser_Tolerance(item);

    MITTRA.Rows[i]["Min_Tol"] = Tolerancechecking.Rows[0]["Min_Tol"].ToString();
    MITTRA.Rows[i]["Max_Tol"] = Tolerancechecking.Rows[0]["Max_Tol"].ToString();

    MITTRA.Rows[i]["Min_Weight"] = Convert.ToDecimal(MITTRA.Rows[i]["MTTRQT"]) - ((Convert.ToDecimal(MITTRA.Rows[i]["MTTRQT"]) * Convert.ToDecimal(MITTRA.Rows[i]["Min_Tol"]) / 10));
    MITTRA.Rows[i]["Max_Weight"] = Convert.ToDecimal(MITTRA.Rows[i]["MTTRQT"]) + ((Convert.ToDecimal(MITTRA.Rows[i]["MTTRQT"]) * Convert.ToDecimal(MITTRA.Rows[i]["Max_Tol"]) / 10));

    dataGrid2.Columns.Clear();
    dataGrid2.ItemsSource = null;
    dataGrid2.ItemsSource = Tolerancechecking.DefaultView;

}


//Working Sum computation
Decimal Sum = Convert.ToDecimal(MITTRA.Compute("SUM(MTTRQT)", string.Empty));  
MaxTol.Text = Sum.ToString();  /*** This is working as i got my value on the text box ****/

尝试对不同列进行总和计算时出错初步尝试

  1. Decimal Sum = Convert.ToDecimal(MITTRA.Compute("SUM(Min_Weight)", string.Empty));

出现错误

Invalid usage of aggregate function Sum() and Type: String.

第二次尝试

  2.  Decimal Sum = Convert.ToDecimal(MITTRA.Compute("SUM(Convert(Min_Weight,'System.Decimal'))", string.Empty));
  3.  Decimal Sum = Convert.ToDecimal(MITTRA.Compute("SUM(Convert(Min_Weight,'System.Decimal'))", ""));

出现错误

Syntax error in aggregate argument: Expecting a single column argument with possible 'Child' qualifier.

我怎样才能让计算总和函数起作用？

Answer 1

感谢@NoChance 提供的解决方案。希望这个post也能帮助到其他人。

/***** This is the part where i declare my datacolumn data type ****/
DataColumn Min_Weight = new DataColumn("Min_Weight");
Min_Weight.DataType = System.Type.GetType("System.Decimal");
MITTRA.Columns.Add(Min_Weight);

/**** This Works finally *****/ 
Decimal Sum = Convert.ToDecimal(MITTRA.Compute("SUM(Min_Weight)", string.Empty)); 
MaxTol.Text = Sum.ToString();

在列中执行计算 SUM() 时出错

Error while performing compute SUM() in a column

c#

wpf

datatable

wpfdatagrid