Adding simple Math column in Gridview

[ggodwin]

I am looking to add a simple math column in Gridview.
basically take the results of Column2 and divide by the number in Column1.

I think this should be simple but I have not found the info searching around.

Column1 = punt_ret_no
Column2 = punt_ret_yds
Column2 = [punt_ret_yds] / [punt_ret_no]

Just for the thread here are my coumns

    <asp:GridView ID="GridView1" AllowSorting="true" runat="server" DataSourceID="SqlDataSource1" OnRowDataBound="GridView1_RowDataBound"
      SkinID="booksSkin" AutoGenerateColumns="False" HorizontalAlign="Left">
      <Columns>
        <asp:BoundField HeaderText="Punt Returns/gm" DataField="punt_ret_no" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Return Yards/gm" DataField="punt_ret_yds" ItemStyle-HorizontalAlign="Center"/>
      </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
      SelectCommand="SELECT [punt_ret_no], [punt_ret_yds] FROM [team_avg] ORDER BY [punt_ret_yds] DESC"
       ConnectionString="<%$ ConnectionStrings:ConnectionString1 %>" />

[Besoup]

so you want column2 to be overwritten with the formula result or are you adding a third column?

[mendhak]

Create new TemplateField column. Add an ItemTemplate to it. Put a label in there.

In the codebehind, handle the rowdatabound event. Get the value of punt_ret_no, get the value of punt_ret_yds, divide. Get the label from the template field. Set the label's text property to that result of your division.

[ggodwin]

Here is what I got and I don't think I am too far off. But I am getting a compilation error. Can anyone see any glaring error I have here?

Compiler Error Message: CS0246: The type or namespace name 'DataTable' could not be found (are you missing a using directive or an assembly reference?)

<%@ Page Language="C#" MasterPageFile="~/AppMaster.master" Title="visualboxscore - CFB Total Offense" %>
<asp:Content ID="Content1" runat="server" ContentPlaceHolderID="mainCopy">
<script runat="server">

    protected void Page_Load(object sender, EventArgs e)
    {

        DataTable dt = new DataTable();

        dt.Columns.Add(new DataColumn("Average"));
        dt.Columns["Average"].Expression = "Return Yards/Punt Returns";

        GridView1.DataSource = dt;

        GridView1.DataBind();
    }


    </script>
<div class="container" style="height: 80%">
    <br>
    <asp:GridView ID="GridView1" AllowSorting="true" runat="server" DataSourceID="SqlDataSource1" OnRowDataBound="GridView1_RowDataBound"
      SkinID="booksSkin" AutoGenerateColumns="False" HorizontalAlign="Center">
     <HeaderStyle HorizontalAlign="Center" />
      <Columns>
        <asp:BoundField HeaderText="Team" DataField="team" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Conf" DataField="team_conf" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Punt Returns" DataField="punt_ret_no" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Return Yards" DataField="punt_ret_yds" ItemStyle-HorizontalAlign="Center"/>
        <asp:TemplateField>
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Eval("Average") %>'></asp:Label>
                </ItemTemplate>
        </asp:TemplateField>    
      </Columns>
    </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
      SelectCommand="SELECT [team], [team_conf], [punt_ret_no], [punt_ret_yds], [punt_ret_td] FROM [team_avg] ORDER BY [punt_ret_yds] DESC"
       ConnectionString="<%$ ConnectionStrings:ConnectionString1 %>" />
</div>
</asp:Content>

[riteshjain1982]

dt.Columns["Average"].Expression = "Return Yards/Punt Returns";

should be

dt.Columns["Average"].Expression = "punt_ret_yds/punt_ret_no";

[ggodwin]

I actually tried that and got the same error.

It acts as if I am getting failure before it gets to that point.

I am getting the "blue squiggly" lines under

Bold code below.

        DataTable dt = new DataTable();

        dt.Columns.Add(new DataColumn

[riteshjain1982]

before that where is team,punt_ret_yds,punt_ret_no etc coulmns in your datatable that you are binding with gridview ?also there should be a check of IsPostback !

 protected void Page_Load(object sender, EventArgs e)
    {

        DataTable dt = new DataTable();

        dt.Columns.Add(new DataColumn("Average"));
        dt.Columns["Average"].Expression = "Return Yards/Punt Returns";

        GridView1.DataSource = dt;

        GridView1.DataBind();
    }

[ggodwin]

Thank you for the help on this.
However, I am confused on your question. [team],etc..are all coming from Gridview1 that is called from the SQL Server.

Below is my entire code that I am using for this page.

I am wondering if my ItemTemplates are getting confused with each other some how?

<%@ Page Language="C#" MasterPageFile="~/AppMaster.master" Title="visualboxscore - CFB Total Offense" %>
<asp:Content ID="Content1" runat="server" ContentPlaceHolderID="mainCopy">
<script runat="server">

  protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {

        if (e.Row.RowType == DataControlRowType.DataRow)
        {

            int row = e.Row.RowIndex + (GridView1.PageSize * GridView1.PageIndex);

            ((Label)e.Row.FindControl("Rank")).Text = (row + 1).ToString();


        } 
    }


    protected void Page_Load(object sender, EventArgs e)
    {

        DataTable dt = new DataTable();

        dt.Columns.Add(new DataColumn("Average"));
        dt.Columns["Average"].Expression = "punt_ret_yds/punt_ret_no";

        GridView1.DataSource = dt;

        GridView1.DataBind();
    }


    </script>
<div class="container" style="height: 80%">
    <br>
    <asp:GridView ID="GridView1" AllowSorting="true" runat="server" DataSourceID="SqlDataSource1" OnRowDataBound="GridView1_RowDataBound"
      SkinID="booksSkin" AutoGenerateColumns="False" HorizontalAlign="Center">
     <HeaderStyle HorizontalAlign="Center" />
      <Columns>
        <asp:TemplateField> 
            <HeaderTemplate>
                Rank
            </HeaderTemplate>
            <itemtemplate> 
                <asp:Label ID="Rank" runat="server" Text="Rank"> </asp:Label>
         </itemtemplate>
        </asp:TemplateField>
        <asp:BoundField HeaderText="Team" DataField="team" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Conf" DataField="team_conf" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Punt Returns" DataField="punt_ret_no" ItemStyle-HorizontalAlign="Center"/>
        <asp:BoundField HeaderText="Return Yards" DataField="punt_ret_yds" ItemStyle-HorizontalAlign="Center"/>
        <asp:TemplateField>
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Eval("Average") %>'></asp:Label>
                </ItemTemplate>
        </asp:TemplateField>    
      </Columns>
    </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
      SelectCommand="SELECT [team], [team_conf], [punt_ret_no], [punt_ret_yds], [punt_ret_td] FROM [team_avg] ORDER BY [punt_ret_yds] DESC"
       ConnectionString="<%$ ConnectionStrings:ConnectionString1 %>" />
</div>
</asp:Content>

[riteshjain1982]

first you are binding gridview as

<asp:GridView ID="GridView1" AllowSorting="true" runat="server" DataSourceID="SqlDataSource1" OnRowDataBound="GridView1_RowDataBound"

but in page load again u r overriding this with

GridView1.DataSource = dt;

where dt has only one column in it

[mendhak]

Add an Imports statement to your page.

Imports System.Data

[ggodwin]

first you are binding gridview as

<asp:GridView ID="GridView1" AllowSorting="true" runat="server" DataSourceID="SqlDataSource1" OnRowDataBound="GridView1_RowDataBound"

but in page load again u r overriding this with

GridView1.DataSource = dt;

where dt has only one column in it

OK, I understand this point.
am I better off having this code handle the entire gridview and eliminate my gridview1 as it is now? Or can I just redirect it so it is not overriding it?

Mendhak....
Is that a solution to what I have now or do I need to clear the above problem first?

[mendhak]

Well, based upon your error:

The type or namespace name 'DataTable' could not be found (are you missing a using directive or an assembly reference?)

It means you're missing a reference. If that's what all the to-and-fro is about, then the Imports should fix it.

[ggodwin]

Well that is all new to me?
What do I do and where do I do it?

[Besoup]

not sure how you do it in C# but in VB it's added at the top of your class:

Imports System.Data

[mendhak]

Because you're using inline ASP.NET code, you'd need to place this under the Page directive.

<%@ import namespace="System.Data" %>

[ggodwin]

Mendhak,

I got that part entered and now I am getting a syntax error?

"Syntax error: Missing operand after 'Yards' operator."}

Here is my code behind.
I am wondering do I need to use the actual SQL column heading's? or my Gridview heading's? I am using the gridview see below.

    protected void Page_Load(object sender, EventArgs e)
    {

        DataTable dt = new DataTable();

        dt.Columns.Add(new DataColumn("Average"));
        dt.Columns["Average"].Expression = "Return Yards/Punt Returns";

        GridView1.DataSource = dt;

        GridView1.DataBind();
    }

[mendhak]

It needs to be the actual SQL column heading.