public void Return_ticket(string iddv)
{
DATVE dv = layOnedatve(iddv);
VEMAYBAY v = layOneVeMayBay(dv.idVe);
v.TrangThai = "Còn vé";
db.DATVEs.Remove(dv);
db.SaveChanges();
}
public void dat_ve_login(DATVE dv)
{
DateTime date = DateTime.Now;
string iddatve = Content.RandomString(12);
dv.idDatVe = iddatve;
dv.NgayDatVe = date;
VEMAYBAY vedangdat = db.VEMAYBAYs.First(m => m.idVe == dv.idVe);
vedangdat.TrangThai = "Hết vé";
db.SaveChanges();
db.DATVEs.Add(dv);
db.SaveChanges();
}