CODEWITHSUNDEEP
c#datatable
lex
lex

Reputation: 31

Datatable columns expression

I am working with an application where user can multiply quantity and price and the results appear in third column using column expression The code i used is showed under this :

       DataTable dt = new DataTable("dtList");
    DataTable dataTable = new DataTable();//Created a new DataTable


        DataColumn dc = new DataColumn();
        dc.DataType = System.Type.GetType("System.Decimal");
        dc.ColumnName = "Price";


      DataColumn dc1 = new DataColumn();
        dc1.DataType = System.Type.GetType("System.Decimal");
        dc1.ColumnName = "qty"; 

          DataColumn dc2 = new DataColumn();
        dc2.DataType = System.Type.GetType("System.Decimal");
        dc2.ColumnName = "Total";
        dc2.Expression = "Price * qty";

       dataTable.Columns.Add(dc);//Add them to the DataTable
        dataTable.Columns.Add(dc1);
        dataTable.Columns.Add(dc2);

       object sumObject;
        sumObject = dt.Compute("Sum(Total)", "");

    I used this code to sum column Total, and show the result in a Text Box, but it's showing an error like this: "Cannot find column [Total]".

My question is what can i change, to make this code work, also sum automatically every time when the user change qty. Sorry for my English and mistakes at my code I am new to WPF

Upvotes: 0

Views: 711

Answers (1)

Juan Carlos Rodriguez
Juan Carlos Rodriguez

Reputation: 784

Giving a fast check to your code I can see one thing.You define a DataTable called dt and then you try to compute the column "dt.Total" but you have never defined a column in you dt.

Try changing your:

sumObject = dt.Compute("Sum(Total)", "");

to

sumObject = dataTable.Compute("Sum(Total)", "");

Edit: By the way, if you do this:

dataTable = new DataTable();//Created a new DataTable


        DataColumn dc = new DataColumn();
        dc.DataType = System.Type.GetType("System.Decimal");
        dc.ColumnName = "Price";


        DataColumn dc1 = new DataColumn();
        dc1.DataType = System.Type.GetType("System.Decimal");
        dc1.ColumnName = "qty";

        DataColumn dc2 = new DataColumn();
        dc2.DataType = System.Type.GetType("System.Decimal");
        dc2.ColumnName = "Total";
        dc2.DefaultValue = 5;
        dc2.Expression = "Price * qty";

        dataTable.Columns.Add(dc);//Add them to the DataTable
        dataTable.Columns.Add(dc1);
        dataTable.Columns.Add(dc2);

Your third column already has the value "price * qty". If you want to show the sum of all your dc Total column just use:

            object sumObject = dataTable.Compute("Sum(Total)", "");

And then 

yourTextbox.Text = sumObject.ToString();

Upvotes: 1

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