Bài 2: Các mô hình dữ liệu (tt) - Pdf 66

Khoa HTTT-Đại học CNTT
1


 

!"#$%&'()*
!"+,-
!".$%/$%
!"!012$%
!"32$%
!"4.&'()*/&'()*
!"5012&'()*
!"678&
!"9#:;<=0>

 
!
!"+,-

#$%&'()*Entity-
Relationship Model?(@:;AB): >-
C+D65"

#:;AB)8EF>G=>(
'(<HI"

 
3
!".$%



Ví dụ.$%PQR: V
01#^?_/_/>-1/
>J8/`8

Ký hiệu
HOCVIEN
Hoten
Gioitinh
Mahv
Ngaysinh
Noisinh

 
6
!"!01+

Đơn trị (Simple)a$%bV0>=cH>?-
01"
Q1F#?/K

Đa hợp (Composite)01V%AB)d
G*N"
Q1FeRfP [/egP ,/SgP ,/hg[  J
01P: P/: .P/: "

Đa trị (Multi-valued)01V%VG>=cA&
?-0$%"
Q1F[ ,[S'Oi[ ,[Sj



Định nghĩa&'()*8$'()*
>JG$%

Ví dụ>$%PQR: ?
.PSV&'()*gP

Ký hiệu\l>0?U
Thuoc
HOCVIEN
LOP
!"4.&'()*+
=K8*J*K

 
++
!"4.&'()*

,$%V%MG
`0&'()*"

Ví dụ
Thuộc
HOCVIEN LOP
Là trưởng lớp

 
+
!"4f&>2&'()*
=K8*K>=KK


Ví dụ.&'()*Giảng dạy>\
$%,R[PQR: /#P P?.PSV
01#>?/#/#*/>=qV
01=_>'J/ 

 
+4
LOP MONHOC
Giang day
GIAOVIEN
'J

012&'()*

 
+5
!"678&
=K8*=J

.&'()*%_'(>
$%/a_'(AB)>0"

Định nghĩa\78&28&B)>&
%?8&B)>&A$%0
AV>?&'()*"

Ký hiệu\78&&%/\78&&A

Ví dụ.$% QK?eK[V

GiaoVien HocVien
ConNguoi
HocVi
NgayVL
NgayNH
Khóa
SoCMND
HoTen
...

 
+
!"6"#&'()*AIJ

Định nghĩa&'()*AB)d
k>0$%J0$%V
&'()*?-1V

Ví dụ#as?_V0>BtI7O=$(*
?>BtI7OAVu>0s?_
NHANVIEN QuanLy
(1,n)
(0,1)

 


Định nghĩa:

.$%'>V01'V


v(*-*?_/-*=B<>-*

Ss>>7>J>?_J-*?-
>/<'w/C"

.B='(I7?_/N
H]J/A%\_"
Khoa HTTT-Đại học CNTT
25
!#x
y
B
z
I
;Ke#K


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