//Hàm nay se duoc thuc thi khi click nut lam moi
private void btnRefresh_Click(object sender, EventArgs e)
{
listEmployee.Clear(); //xoa het cac nhan vien hiện có trong danh sach
LoadDataFromFile(filePath); //doc lai file
ShowListEmployeeToDatagridView(listEmployee); //hien thi lai danh sach
}
private void btnRefresh_Click(object sender, EventArgs e)
{
dgvListEmployee.Rows.Clear();
listEmployee.Clear();
LoadDataFromFile(filePath);
}