How to check id in database and display the name on label

Question

I'm working on the Registration page for Lucky Draw system.So the process for registration is user need to scan their barcode using usb barcode scanner. I stuck on that part which i cannot check the employee id on database after user scan or type in the textbox. I also want to display the employee name after scan the barcode.Can anyone give me some ideas/solution.

 

Below is my database:

 

 

 

Code : 

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class Attendance : System.Web.UI.Page
{
    SqlCommand cmd = new SqlCommand();
    SqlConnection con = new SqlConnection();
    string str;
    private string connectionString;

    protected void Page_Load(object sender, EventArgs e)
    {
        con.ConnectionString = @"Data Source= (LocalDB)\MSSQLLocalDB; AttachDbFilename =
          C:\Users\Nor  Asyraf  Mohd No\source\repos\LuckyDraw\LuckyDraw\App_Data\ticket.mdf;
            Integrated Security = True";
        txtText.Focus();
    }

    protected void btnSave_Click(object sender, EventArgs e)
    {
        idcheck();
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            using (SqlCommand command = connection.CreateCommand())
            {
                command.CommandText = "UPDATE EMPLOYEES SET Attendance = 'Present' WHERE EMP_ID = @id";
                command.Parameters.AddWithValue("@id", txtText.Text);
                connection.Open();

                command.ExecuteNonQuery();

                connection.Close();
            }
        }
    }

public void idcheck()
        {
        string query = "select EMP_ID from EMPLOYEES where EMP_ID='" + txtText.Text + "'";
        SqlDataAdapter ada = new SqlDataAdapter(query, con);
        DataTable dt = new DataTable();
        ada.Fill(dt);
        if (dt.Rows.Count > 0)
        {
            lblError.Text = dt.Rows[0]["EMP_NAME"].ToString();
        }
    }
    protected void Button1_Click1(object sender, EventArgs e)
    {
        Response.Redirect("Default.aspx");
    }
}