cum4

create table IDThiSinhDaDuThi (
  IdKyThi varchar(255) REFERENCES KyThi(IdKyThi), 
  IdThiSinhDaDuThi varchar(255),  
  PRIMARY KEY (IdKyThi, IdThiSinhDaDuThi));
create table BangTraLoiCuaThiSinh (
  IdBangTraLoi varchar(255), 
  IdBaiThi varchar(255) REFERENCES BaiThiKyNang(IdBaiThi), 
  HoVaTenThiSinhTraLoi varchar(255),
  NgayGioThucHien timestamp with time zone,
  ThoiLuongThucHien interval,
  TongDiemBaiThi real, 
  IdThiSinh varchar(255) REFERENCES ThiSinh(IdThiSinh),
  PRIMARY KEY (IdBangTraLoi));
create table LuaChon (
  SoThuTuLuaChon varchar(255), 
  IdCauHoi varchar(255) REFERENCES CauHoiTracNghiem(IdCauHoi), 
  LuaChonDung varchar(255), 
  Diem real , 
  VanBanLuaChon TEXT, 
  PRIMARY KEY (SoThuTuLuaChon, IdCauHoi));
create table CauTraLoi (
  SoThuTuDaLuaChon varchar(255), 
  IdCauHoi varchar(255) REFERENCES CauHoiTracNghiem(IdCauHoi), 
  IdBangTraLoi varchar(255) REFERENCES BangTraLoiCuaThiSinh(IdBangTraLoi),  
  PRIMARY KEY (IdCauHoi, IdBangTraLoi));