Error Page ASP.NET C# with query string

Errorpage.aspx page

 aspx page

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">

</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">

    <div><asp:Literal runat="server" ID="ltrError"></asp:Literal></div>

    <div class="h1 text-center text-danger">

        Oops

        <br />

        <h1 class="text-warning">something went wrong !!!</h1>

        <br />

        <div style="font-size:46px" class="text-success">Sorry for the Inconvenience</div>

        <br />

        <br />

    </div>

</asp:Content>

aspx.cs

 public partial class WebForm19 : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            try

            {

                string r = Request.QueryString["r"].ToString();

                ltrError.Text = r;

            }

            catch

            {

                ltrError.Text = "";

            }

        }

    }

------------------------

catch()

{

Response.Redirect("ErrorPage.aspx?r=" + ex.Message);

}

Serial number grid PHP

  <?php

$s=mysql_query("SELECT * FROM  bus_detail where source_point='$_SESSION[source_point]' && destination_point='$_SESSION[destination]'");
$counter = 0;
while($row=mysql_fetch_array($s))
{
?>    
 <tr>
<td><?php echo ++$counter; ?></td>
<td><?php echo $row['bus_name'];?> </td>    
<td><?php echo $row['bus_no'];?></td> 
</tr>
<?php }?>

reference:- https://stackoverflow.com/questions/20322869/how-to-create-serial-number

Out Parameter in ASP.NET C#

we donot have to give it's value(intialize it's value)

 DateTime LastDate;

            string TransferCycleCategory = CheckTransferCycleCategory(FMSID, out LastDate);

 public string CheckTransferCycleCategory(Int64 FMSID, out DateTime LastDate)

    {

        DataTable dt = Repository.GetCurrentTransferCycle();

        DateTime StartDate = Convert.ToDateTime(dt.Rows[0]["StartDate"]);

        DateTime EndDate = Convert.ToDateTime(dt.Rows[0]["EndDate"]);

        string TransferCycleType = dt.Rows[0]["TransferCycleType"].ToString();

        LastDate = StartDate;

        return TransferCycleType;

    }

reference:- https://www.tutorialspoint.com/difference-between-out-and-ref-keyword-in-chash

Serial number in select query SQL

 select ROW_NUMBER() OVER (ORDER BY name ASC) AS SrNo,* from icms_employee e inner join  (select max(id) as maxid , Discipline from icms_employee group by Discipline ) t on  e.id = t.maxid

Max group by SQL query with all columns

 select * from icms_employee e inner join  (select max(id) as maxid , Discipline from icms_employee group by Discipline ) t on  e.id = t.maxid

reference:- https://stackoverflow.com/questions/6860746/sql-selecting-multiple-columns-based-on-max-value-in-one-column