How to display record in Crystal Report?

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;
using CrystalDecisions.Web;
using CrystalDecisions.ReportSource;

public partial class Default2 : System.Web.UI.Page
{
    SqlConnection sqlcon = new SqlConnection(ConfigurationManager.ConnectionStrings["Con"].ConnectionString);
    SqlCommand sqlcmd;
    SqlDataAdapter da;
    DataTable dt = new DataTable();
    string sid,query;
     protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            sid = Request.QueryString["sid"];
            try
            {
                sqlcon.Open();
                //Check whether query string have value or not if not have value then select all record in below query otherwise select particular record with help of where condition
                if(sid=="" || sid==null)
                {
                    query="select * from student";
                }
                else
                {
                    query="select * from student where sid='" + sid +"'";
                }
                sqlcmd = new SqlCommand(query,sqlcon);
                da = new SqlDataAdapter(sqlcmd);
                dt.Clear();
                da.Fill(dt);
                if (dt.Rows.Count > 0)
                {
                    ReportDocument RptDoc = new ReportDocument();

                    RptDoc.Load(Server.MapPath("~/CrystalReport.rpt"));
                    RptDoc.SetDataSource(dt);

                    CrystalReportViewer1.ReportSource = RptDoc;
                    CrystalReportViewer1.DataBind();                 
                }
            }
            catch(Exception ex)
            {
                Response.Write(ex.ToString());
            }
            finally
            {
                sqlcon.Close();
            }                
        }
    }
}