Hello

I am following this link: 

Prevent (Avoid) Duplicate (Double) record insert into Database in ASP.Net

When i press the button insert data 2 times still not tell me its Duplicate record.

I am focus Duplicate record by DateStart and DatEnd (date)

Users sometimes make Duplicate record

I want stop this Duplicate record by DateStart and DatEnd (date)

protected void Insert2(object sender, EventArgs e)
{
    if (txtUsername.Text == String.Empty)
    {
        ClientScript.RegisterStartupScript(this.GetType(), "randomtext", " alertmecheck()", true);
    }
    else if (ddlCountries.SelectedItem.Text == String.Empty)
    {
        ClientScript.RegisterStartupScript(this.GetType(), "randomtext", " alertmecheck1()", true);
    }
    else if (ddlStates.SelectedItem.Text == String.Empty)
    {
        ClientScript.RegisterStartupScript(this.GetType(), "randomtext", " alertmecheck2()", true);
    }
    else if (ddlCities.SelectedItem.Text == String.Empty)
    {
        ClientScript.RegisterStartupScript(this.GetType(), "randomtext", " alertmecheck3()", true);
    }
    else
    {

        ReportViewer1.ProcessingMode = ProcessingMode.Local;
        ReportViewer1.LocalReport.ReportPath = Server.MapPath("~/repotfolder/ReportVback.rdlc");

        ReportParameter[] param = new ReportParameter[13];
        param[0] = new ReportParameter("Reportbackname", txtUsername.Text);
        param[1] = new ReportParameter("Reportbackjoptitil", joptitel.Text);

        param[3] = new ReportParameter("Reportbackeldarajah", eldarajah.Text);
        param[4] = new ReportParameter("Reportbackfileid", filenumber.Text);
        param[5] = new ReportParameter("Reportbackcivilid", civilid.Text);
        param[6] = new ReportParameter("Reportbackdatestart", txtBoxDate8.Text);
        param[7] = new ReportParameter("Reportbackdateend", txtBoxDate10.Text);
        param[8] = new ReportParameter("Reportbackdateorderfromstart", txtBoxDate7.Text);
        param[11] = new ReportParameter("Reportbackdateorderfromback1", txtBoxDate11.Text);
        param[9] = new ReportParameter("Reportbackvacationback", ddlPC.Text);
        param[10] = new ReportParameter("Reportbacknote", textmsg.Text);
        param[2] = new ReportParameter("Reportbackqsem", ddlCities.SelectedItem.Text);
        param[12] = new ReportParameter("ReportbackStates", ddlStates.SelectedItem.Text);

        ReportViewer1.LocalReport.SetParameters(param);
        ReportViewer1.LocalReport.DataSources.Clear();
        ReportViewer1.LocalReport.Refresh();
        int recordsInserted = 0;
        string sql = "IF NOT EXISTS(SELECT * FROM Table_vacation WHERE idnamev = @idnamev and idcivilv = @idcivilv and datestart = @datestart and dateend = @dateend) ";
        sql += "BEGIN ";
        sql += "insert into Table_vacation (note,vacationdataback,States,idnamev,jop,eldarajah,el3malv,datesp10,idcivilv,datestart,dateend,vacationdata,totalva,infovacation,namevacation,iPAddress,dataaddtime,edit) VALUES (@note,@vacationdataback,@States,@idnamev,@jop,@eldarajah,@el3malv,@datesp10,@idcivilv,@datestart,@dateend,@vacationdata,@totalva,@infovacation,@namevacation,@iPAddress,@dataaddtime,@edit) ";
        sql += "END";

        string usernamemove = this.Page.User.Identity.Name;
        string constr = ConfigurationManager.ConnectionStrings["cmConnectionString"].ConnectionString;
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand(sql))
            {
                cmd.Connection = con;
                cmd.Parameters.AddWithValue("@idnamev", txtUsername.Text);
                cmd.Parameters.AddWithValue("@jop", joptitel.Text);
                cmd.Parameters.AddWithValue("@eldarajah", eldarajah.Text);
                cmd.Parameters.AddWithValue("@el3malv", ddlCities.SelectedItem.Text);
                cmd.Parameters.AddWithValue("@datesp10", filenumber.Text);
                cmd.Parameters.AddWithValue("@idcivilv", civilid.Text);
                cmd.Parameters.AddWithValue("@datestart", txtBoxDate8.Text);
                cmd.Parameters.AddWithValue("@dateend", txtBoxDate10.Text);
                cmd.Parameters.AddWithValue("@vacationdata", txtBoxDate7.Text);
                cmd.Parameters.AddWithValue("@vacationdataback", txtBoxDate11.Text);
                cmd.Parameters.AddWithValue("@totalva", lblLabel2.Text);
                cmd.Parameters.AddWithValue("@infovacation", ddlPC.Text);
                cmd.Parameters.AddWithValue("@namevacation", "اقرار عودة");
                cmd.Parameters.AddWithValue("@States", ddlStates.SelectedItem.Text);
                cmd.Parameters.AddWithValue("@iPAddress", usernamemove);
                cmd.Parameters.AddWithValue("@dataaddtime", Convert.ToDateTime(DateTime.Now.ToLongTimeString()));
                cmd.Parameters.AddWithValue("@edit", "(جديد)");
                cmd.Parameters.AddWithValue("@note", textmsg.Text);
                cmd.Connection = con;
                con.Open();
                recordsInserted = cmd.ExecuteNonQuery();
                this.BindGrid();
                this.BindGridView();
                con.Close();
            }
        }

        if (recordsInserted == -1)
        {
            ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('Duplicate record. Please insert Unique data.');", true);
        }

        //insert date vacation into user data start date vacation to end date vacation
        using (con = new SqlConnection(constr))
        {
            string query = "UPDATE Table_infoname SET DateTimePicker1 = @DateTimePicker1,DateTimePicker2 = @DateTimePicker2 WHERE civilid = @Civilid";
            using (cmd = new SqlCommand(query))
            {
                cmd.Connection = con;
                cmd.Parameters.AddWithValue("@civilid", civilid.Text.ToString());

                cmd.Parameters.AddWithValue("@DateTimePicker1", txtBoxDate8.Text.ToString());
                cmd.Parameters.AddWithValue("@DateTimePicker2", txtBoxDate10.Text.ToString());

                cmd.Connection = con;
                con.Open();
                cmd.ExecuteNonQuery();

                con.Close();
            }
        }

        Warning[] warnings;
        string[] streamIds;
        string contentType;
        string encoding;
        string extension;

        //Export the RDLC Report to Byte Array.
        byte[] bytes = ReportViewer1.LocalReport.Render(rbFormat.SelectedItem.Value, null, out contentType, out encoding, out extension, out streamIds, out warnings);

        //Download the RDLC Report in Word, Excel, PDF and Image formats.
        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "";
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        Response.ContentType = contentType;
        Response.AppendHeader("Content-Disposition", "attachment; filename=اقرار عودة - " + DateTime.Now.ToString("dd/MM/yyy - ") + txtUsername.Text + "." + extension);
        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.End();
    }
}