private void ListarXDnioCod()
{
if (txtbuscar.Text == "")
{
CargarGrilla();
}
else
{
dgvAlumno.DataSource = alumno.ListarXDnioCod(txtbuscar.Text);
dgvAlumno.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
dgvAlumno.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells;
dgvAlumno.AllowUserToAddRows = false;
dgvAlumno.AllowUserToDeleteRows = false;
dgvAlumno.ReadOnly = true;
}
}