consulta.aspx.cs

using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication1
{
    public partial class consulta : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void find_Click(object sender, EventArgs e)
        {
            string s = System.Configuration.ConfigurationManager.ConnectionStrings["cadenaconexion1"].ConnectionString;
            SqlConnection conexion = new SqlConnection(s);
            conexion.Open();
            SqlCommand comando = new SqlCommand("select dni,apellidonom,provincia from alumnos " +
                  " where dni='" + this.dni.Text + "'", conexion);
            SqlDataReader registro = comando.ExecuteReader();
            if (registro.Read())
                this.Label1.Text = "Nombre:" + registro["apellidonom"] + "<br>" +
                                   "Provincia:" + registro["provincia"];
            else
                this.Label1.Text = "No existe un alumno con ese dni";
            conexion.Close();
        }
    }
}