ER?EER??????

1
ER?EER??????
? 7 ?
2
????

• ?ER???????????
• ??1?????????
• ??2????????
• ??3??11???????
• ??4??1N???????
• ??5??MN???????
• ??6???????
• ??7N????????
• ?EER???????
• ??8??????????
• ??9????(??)???

3
COMPANY????ER?????
4
COMPANY?ER???????????
5
??1????????? (1/3)

• ?????????(Entity Type),??????(relation),??????????
  ?
• ??(Attributes)??
• ??????(Simple Attributes)
• ??????(Composite Attribute),????????????????(Simpl
  e Attributes)
• ??(Primary key)
• ??? ??(key Attribute) ????

6
??1????????? (2/3)
7
??1????????? (3/3)
8
??2???????? (1/2)

• ?????????W??????R
• ??
• W?????????????????????
• ?????(owner)???????????(?????)
• ??
• ????????????W????????

9
??2???????? (2/2)
10
??3??11??????? (1/2)

• ??11??????3????????
• ?????????????S??,?S??????????T???
• ???????????(total participation)R????????S
• ??????????????,?????????????
• ??????????????,???????
• ??????????????3???R,?????????S?T???

11
??3??11??????? (2/2)
????1???
12
??4??1N??????? (1/4)

• ?????????1N????R
• ????S???????????N??(N-side)????
• ?????R???????????T???,??S???S????
• ???1N????????????S?,??S???

13
??4??1N??????? (2/4)
14
??4??1N??????? (3/4)
15
??4??1N??????? (4/4)
16
??5??MN??????? (1/2)

• ??????MN????R
• ????????S???R
• ????????R??? ????? (???????????????)
• ???????(?????????????)

17
??5??MN??????? (2/2)
18
??6??????? (1/2)

• ????????A
• ????????S???R
• ??S ???A??? ??????K (??S????)
• ???A?K???

19
??6??????? (2/2)
20
??7N???????? (1/2)

• ?????n??????R(n gt 2)
• ???????S???R
• ????????R??? n ???? (???????????????)
• ??n ????(?????????????)

21
??7N???????? (2/2)
22
ER???????????

23
ER????? (1/2)
24
ER????? (2/2)
25
ER????? (1/2)
26
ER????? (2/2)
27
ER????? (1/3)
28
ER????? (2/3)
SHIP
Sname Owner Type SCname Pname
SHIP_TYPE
Type Tonnage Hull
STATE_COUNTRY
SC_Name Continent
SEA_OCEAN_LAKE
SOL_Name
29
ER????? (3/3)
SHIP_MOVEMENT
Sname Date Time Longitude Latitude
PORT
SC_Name Pname SOL_Name
PORT_VISIT
VSname VPname VSC_Name StartDate EndDate
30
ER????? (1/2)
31
ER????? (2/2)
32
??8??????????(1/6)

• ???m???? S1, S2,.,Sm ??????C
• ??C???? k,a1,an,???k
• ??Attrs(R)?PK(R)????R??????
• ????????????4???
• ??8A????-?????C???(L)????Si???(Li)
• ??L??Attri(L) k,a1,an ???PK(L) k
• ??Li??Attrs(Li) k ? Si???,???PK(Li)k?
• ??????????????(???????????)
• ??8B????-??????Si???(Li)
• ??Li??Attrs(Li) k,a1,an ? Si???
  ,???PK(Li)k?
• ?????????????????

33
??8??????????(2/6)

• ??8C????(??????)-??????(L)
• ??Attri(L) k,a1,an?S1??? ? Sm??? ?t
• t ??????????(type or discriminating
  attribute),???????????????
• ????PK(L) k
• ?????????????????
• ??8D????(??????) -??????(L)
• ??Attri(L) k,a1,an?S1??? ? Sm??? ?t1,
  t2,,tm
• ti?????????(Boolean type attribute),?????????????S
  i
• ????PK(L) k
• ????????????????????

34
??8??????????(3/6)
??????8A
35
??8??????????(4/6)
??????8B
36
??8??????????(5/6)
??????8C
37
??8??????????(6/6)
??????8D
38
????????????(1/3)

• ?????(????)????????????(??4.7)
• ????????????????
• ??,?4.7??7.6???
• ??8APERSON/EMPLOYEE, ALUMNUS, STUDENT
• ??8C EMPLOYEE/STAFF, FACULTY,
  STUDENT_ASSISTANT
• ??8D
• STUDENT/STUDENT_ASSISTANT (in STUDENT)
• STUDENT/GRADUATE_STUDENT, UNDERGRADUATE_STUDENT
• STUDENT_ASSISTANT/RESEARCH_ASSISTANT,
  TEACHING_ASSISTANT

39
????????????(2/3)
40
????????????(3/3)
41
?????(????)???(1/2)

• ?????????????????,?????????????????????????,??????
  ?????????
• ?4.6??ENGINEERING_MANAGER??????
• ?4.7??STUDENT_ASSISTANT??????
• ???????,??????8??????????????
• ?7.6?STUDENT_ASSISTANT,??????8C?8D
• ??8C???EMPLOYEE?? (Employee_type??)
• ??8D???STUDENT?? (Stud_assist_flag??)

42
?????(????)???(2/2)
43
??9????(??)??? (1/3)

• ?????????????????????,?????????????
• ?????????????????,?????????? (surrogate key)
  ??????
• ??4.8???,???????OWNER???????OWNER,???????????????
• OWNER???????OwnerId

44
??9????(??)??? (2/3)
45
??9????(??)??? (3/3)