Come distribuire le colonne dell'istogramma ASP.NET su intervalli rilevanti dell'asse X?

Si prega di vedere sotto il tuo ASPX originale modificato per adattarsi al risultato desiderato. Fondamentalmente devi fare in modo che l'intervallo della griglia principale sia lo stesso dell'intervallo di punteggio e rendere ogni XValue essere il punto medio di ogni intervallo. Inoltre, per fare in modo che le tue colonne riempiano completamente il vuoto, devi impostare la proprietà personalizzata PointWidth=1 .

ASPX:

       <asp:Chart ID="Chart2" runat="server"  BackColor="DarkSlateBlue" BackGradientStyle="LeftRight"  
       BorderlineWidth="0" Height="440px" Palette="SeaGreen" PaletteCustomColors="24, 0, 0"  
       Width="560px" BorderlineColor="128, 128, 255" OnLoad="Chart2_Load">

            <Titles>
                <asp:Title Name="DefaultTitle" Font="Trebuchet MS, 15pt, style=Bold"
                           Text = "Students per Total Score Achieved" />
            </Titles>
            <%-- <Legends>
                     <asp:Legend Name="DefaultLegend" Enabled="True" Docking="Top" />
            </Legends>--%>

            <Series>
                <asp:Series Name="Series1" YValuesPerPoint="1" CustomProperties="PointWidth=1">
                    <Points>
                        <asp:DataPoint Color="GreenYellow" XValue="15" YValues="25" />
                        <asp:DataPoint Color="255, 255, 128" XValue="25" YValues="15" />
                        <asp:DataPoint Color="0, 192, 192" XValue="35" YValues="10" />
                        <asp:DataPoint Color="Khaki" XValue="45" YValues="35" />
                    </Points>
                </asp:Series>
            </Series>
            <ChartAreas>
                <asp:ChartArea Name="ChartArea1" >
                    <AxisY Title="No of Students ">
                        <MajorGrid LineColor="DarkGray" LineDashStyle="Dot" />
                    </AxisY>
                    <AxisX Title="Score Achieved" Minimum="0" Enabled="True">
                        <MajorGrid Interval="10" IntervalOffset="Auto" IntervalOffsetType="Number" IntervalType="Number" LineColor="DarkGray" LineDashStyle="Dot" />
                        <MajorTickMark Interval="10" IntervalOffset="Auto" IntervalOffsetType="Number" IntervalType="Number" />
                    </AxisX>
                    <AxisY2>
                        <LabelStyle TruncatedLabels="True" />
                    </AxisY2>
                </asp:ChartArea>
            </ChartAreas>
        </asp:Chart>

MODIFICA: Si noti che il colore per ogni punto viene assegnato in modo esplicito nel file aspx. Puoi fare la stessa cosa nel code-behind utilizzando colori predefiniti da una raccolta o generare colori casuali, in questo modo:

Random r = new Random();
foreach (DataPoint dp in Chart2.Series[0].Points)
    dp.Color = Color.FromArgb(255, r.Next(100, 255), r.Next(100, 255), r.Next(100, 255));

EDIT 2: Questo è esattamente come appare il mio codice ora:

ASPX:

   <asp:Chart ID="Chart2" runat="server"  BackColor="DarkSlateBlue" BackGradientStyle="LeftRight"  
   BorderlineWidth="0" Height="440px" Palette="SeaGreen" PaletteCustomColors="24, 0, 0"  
   Width="560px" BorderlineColor="128, 128, 255" OnLoad="Chart2_Load">

        <Titles>
            <asp:Title Name="DefaultTitle" Font="Trebuchet MS, 15pt, style=Bold"
                       Text = "Students per Total Score Achieved" />
        </Titles>
        <%-- <Legends>
                 <asp:Legend Name="DefaultLegend" Enabled="True" Docking="Top" />
        </Legends>--%>

        <Series>
            <asp:Series Name="Series1" YValuesPerPoint="1" CustomProperties="PointWidth=1">
            </asp:Series>
        </Series>
        <ChartAreas>
            <asp:ChartArea Name="ChartArea1" >
                <AxisY Title="No of Students ">
                    <MajorGrid LineColor="DarkGray" LineDashStyle="Dot" />
                </AxisY>
                <AxisX Title="Score Achieved" Minimum="0" Enabled="True">
                    <MajorGrid Interval="10" IntervalOffset="Auto" IntervalOffsetType="Number" IntervalType="Number" LineColor="DarkGray" LineDashStyle="Dot" />
                    <MajorTickMark Interval="10" IntervalOffset="Auto" IntervalOffsetType="Number" IntervalType="Number" />
                </AxisX>
                <AxisY2>
                    <LabelStyle TruncatedLabels="True" />
                </AxisY2>
            </asp:ChartArea>
        </ChartAreas>
    </asp:Chart>

CS:

protected void Chart2_Load(object sender, EventArgs e)
{
    Chart2.Visible = true;
    /*
    SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["Con"].ConnectionString);

    SqlCommand cmd = new SqlCommand();
    cmd.Connection = connection;
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.CommandText = "sp_range";
    cmd.Parameters.AddWithValue("@sub_code", DropDown_Subjects.SelectedItem.Value);

    //  cmd.ExecuteNonQuery();

    connection.Open();
    SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
    */

    Chart2.DataSource = dt;

    Chart2.Series[0].XValueMember = "Score_Achieved";
    Chart2.Series[0].YValueMembers = "No_of_Students";

    Chart2.DataBind();

    Random r = new Random();
    foreach (DataPoint dp in Chart2.Series[0].Points)
        dp.Color = Color.FromArgb(255, r.Next(100, 255), r.Next(100, 255), r.Next(100, 255));

    //connection.Close();
}