Search not working when button is clicked

It does not show the searched items when I type in a name.

What I did to search for aspx

 <input type="text" class="field" id="searchtextbox"/>
 <input type ="button" class="search-submit" value="Search" onclick="search();"/>
 <script type ="text/javascript">
            function search() {
                window.location = "Events.aspx?search=" + document.getElementById("searchtextbox").value;
            }  
        </script> 

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Code behind. Those bolded are what I did to search
protected void Page_Load(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection(_connStr);
        con.Open();
        SqlCommand cmd = con.CreateCommand();
        // event types
        string sql = "Select * from [EventType] order by 1";
    cmd.CommandText=sql;
      DataTable dtet = new DataTable();
    SqlDataAdapter daet = new SqlDataAdapter(cmd);
    daet.Fill(dtet);
      dd.DataSource = dtet;
      dd.DataBind();

      // events
      int EventTypeID = 0;
      if (Request.QueryString["type"] != null)
        EventTypeID = Convert.ToInt32(Request.QueryString["type"].ToString());
      if (EventTypeID == 0)
        sql = "select * from EventDetail order by EventDetail_ID";
      else
        sql = "select * from EventDetail where EventType_ID=" + EventTypeID.ToString() + " order by EventDetail_ID";

   if(Request.QueryString["type"] != null && Request.QueryString["search"] != null)
        {
            sql = "select * from EventDetail where =eventDetailName like('% " + Request.QueryString["search"].ToString() + "%')";

        }

        cmd.CommandText=sql;
      DataTable dte = new DataTable();
    SqlDataAdapter dae = new SqlDataAdapter(cmd);
    dae.Fill(dte);
          d1.DataSource = dte;
          d1.DataBind();
          con.Close();
    }