Try this....
string strEmpName = TextBox1.Text;
cmd = new SqlCommand("SELECT empname FROM emptable WHERE id ='"+id+"'", sqlcon);
con.Open();
cmd.ExecuteNonQuery();
SqlDataReader dr;
dr = cmd1.ExecuteReader();
if (dr.HasRows)
{
dr.Read();
txtEmpName.Text = Convert.IsDBNull(dr["empname "]) ? "" : Convert.ToString(dr["strEmpName"]);
}
con.Close();