-- BTVN 
-- Cho biet Sinh vien thi khong dau ( Diem < 5 ) mon cau truc du lieu 1 nhung chua thi lai 
select SinhVien.* from SinhVien
left join KetQua on KetQua.MaSV = SinhVien.MaSV
left join MonHoc on KetQua.MaMH = MonHoc.MaMH
where MonHoc.MaMH = 'THCS01' -- Sinh vien hoc mon Cau Truc Du Lieu 1
and KetQua.LanThi = 1 -- Co di thi ( Thi lan 1 )
and KetQua.Diem < 5 -- Ket qua thi duoi 5
and SinhVien.MaSV not in -- và khong thuoc ve 
(
select SinhVien.MaSV from SinhVien
left join KetQua on KetQua.MaSV = SinhVien.MaSV
left join MonHoc on KetQua.MaMH = MonHoc.MaMH
where MonHoc.MaMH = 'THCS01' -- Sinh vien hoc mon cau truc du lieu 1
and KetQua.LanThi > 1 -- thi hon 1 lan 
)