1. EDUOPEN Carlo Batini University of Milano Bicocca, Italy batini@disco
EDUOPEN Carlo Batini University of Milano Bicocca, Italy Assignment on Conceptual design

2. Diagrammatic representation adopted

3. Diagrammatic representation
Construct of the ER model
Diagrammatic representation
Entity
Attribute of entity
Relationship
Attribute of relationship
Is-a hierarchy
Generalization hierarchy
Internal Identifier
External Identifier
Name
Name
Name of attribute
Name
Name
Name of attribute
Name
Name of attribute
Name of attribute
Name
Name

4. Furthermore…
When the internal identifier is made of two/n attributes we will write:
Att1 &
Att2 &
….. ……
Attn
Name

5. Certification Exercise - 1
Read carefully the following requirements

6. Structure of requirements in six parts
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type. R2 - Each bike is identified by a numeric code, and a date of purchase; assisted bikes have a make, that may change among bikes (we do not represent the makes of normal bikes). R3 - When bikes are not used, they are parked in locations of parking lots. As a consequence, for each bike and for each minute in the year (e.g. minute 34 of hour 10 a.m. of march 7th) we want to represent the state of the bike, namely if it is parked or it is in motion. Furthermore, for each minute in the year and each location in a parking lot, we want to represent, separately, which bike is possibly parked in the location (e.g. in minute 29 of hour 11 a.m. of march 21th bike 73 is parked in location 15 of parking lot 28, while in the same minute bike 130 is parked in location 6 of parking lot 112). Of course, if in a given minute a bike is in motion, the corresponding location in a parking lot does not exist, and, therefore, will not be represented. It is strongly recommended to represent the concept of minute with an Entity. R4 – In order to use bikes, users have to register themselves. A registered user is characterized by an identifier (e.g. a fiscal code, or a social security number), a progressive numeric code (first person registered, second person registered, etc.) a name, a surname, date of birth, municipality of birth, with code, name of municipality and region (we assume that municipalities are located in regions). R5 – Everytime a user picks up and subsequently returns a bike, such an event (pick up and return of a bike by a user) has to be recorded. The event is identified by a progressive number in the year (e.g. first event in 2015, second event in 2015, etc.) and duration (e.g. 12 minutes, 47 minutes); such duration has to be explicitely represented in the data base. The minute of pick up and the minute of return have to be associated to the event, besides, of course, the bike used and the user involved. R6 – One or more credit cards are associated to users, with type (e.g. Visa, Diners), progressive code in the card type, and daily maximum amount of withdrawal (that depends on the card and on the person). You have to represent above requirements with an Entity Relationship Schema, in terms of entities, relationships, attributes, internal and external idetitifers, generalizations, is-a relationships, minimum and maximum cardinalities.

7. Certification Exercise - 2
For requirements R1 to R6 you have to choose among the several schemas proposed a schema representing requirements
Once you have chosen the schema for, say, requirements R1, the correct solution among schemas proposed is shown to you; at this point, you have to move to requirements R2, and so on, until you reach requirements R6.
At this point the self assessment is finished.

8. Grades for the correct solution
Requirements
Grade of the correct solution R1 15 R2 10 R3 25 R4 R5 R6
Total
100

9. Requirements R1 (15 points)

10. Requirements R1
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type.

11. R1 - Choose among the following cases
(1,1)
(1,n)
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Parking
(Lot) in B
# numeric code
Type of bike
(1,1)
(1,n) in
Parking
Code
Longitude &
Latitude
Address
Name
# of locations
Location C
(1,n)
(1,n) in
Parking
Code
Longitude &
Latitude
Address
Name
# of locations
# numeric code
Type of bike
Location D
# numeric code
Type of bike
(1,1)
(1,n)
Code
Longitude &
Latitude
Address
Name
# of locations
Location in
Parking

12. Requirements R1 Grades for the four solutions
Grade of the correct solution A 15 B 9 C 5 D

13. Correct solution for requirements R1
# numeric code
Type of bike
(1,1)
(1,n)
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Parking
(Lot) in

14. Requirements R2 (10 points)

15. Requirements R2
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type.
R2 - Each bike is identified by a numeric code, and a date of purchase; assisted bikes have a make, that may change among bikes (we do not represent the makes of normal bikes).

16. Choose among the following cases
Bike
Code
Date of purchase
Make A
Bike
Assisted
Code
Date of purchase
make B
Bike
Normal
Code
Date of purchase
Assisted
make C
Bike
Code
Date of purchase
Type
Make D

17. Requirements R2 Grades for the four solutions
Grade of the correct solution A B 10 C D 7

18. Correct solution for requirements R1+R2
(1,1)
(1,n)
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Parking
(Lot) in
Bike
Normal
Code
Date of purchase
Assisted
make

19. Requirements R3 (20 points)

20. Requirements R3
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type.
R2 - Each bike is identified by a numeric code, and a date of purchase; assisted bikes have a make, that may change among bikes (we do not represent the makes of normal bikes).
R3 - When bikes are not used, they are parked in locations of parking lots. As a consequence, for each bike and for each minute in the year (e.g. minute 34 of hour 10 a.m. of march 7th) we want to represent the state of the bike, namely if it is parked or it is in motion. Furthermore, for each minute in the year and each location in a parking lot, we want to represent, separately, which bike is possibly parked in the location (e.g. in minute 29 of hour 11 a.m. of march 21th bike 73 is parked in location 15 of parking lot 28, while in the same minute bike 130 is parked in location 6 of parking lot 112). Of course, if in a given minute a bike is in motion, the corresponding location in a parking lot does not exist, and, therefore, will not be represented. It is strongly recommended to represent the concept of minute with an Entity.

21. Requirements R3
Before your modeling of requirements, let us split requirements in R3 into two different paragraphs. R3.1 - When bikes are not used, they are parked in locations of parking lots. As a consequence, for each bike and for each minute in the year (e.g. minute 34 of hour 10 a.m. of march 7th) we want to represent the state of the bike, namely if it is parked or it is in motion. R3.2 - Furthermore, for each minute in the year and each location in a parking lot, we want to represent, separately, which bike is possibly parked in the location (e.g. in minute 29 of hour 11 a.m. of march 21th bike 73 is parked in location 15 of parking lot 28, while in the same minute bike 130 is parked in location 6 of parking lot 112). Of course, if in a given minute a bike is in motion, the corresponding location in a parking lot does not exist, and, therefore, will not be represented. It is strongly recommended to represent the concept of Minute with an Entity.

22. Solution A Location Parking Minute In 2015 Bike Assisted Normal (1,1)
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
State
(1,n)
Bike
Code
Date of purchase
Assisted
make
Normal

23. Solution B Location Parking Minute In 2015 Bike Assisted Normal (1,1)
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,1)
Parked in
(1,1) On
(1,n)
State
Bike
Code
Date of purchase
(1,n)
Assisted
make
Normal

24. Solution D Location Parking Minute In 2015 Bike Assisted Normal (1,1)
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
(1,n)
Parked in
State
(1,n)
Bike
Code
Date of purchase
Assisted
make
Normal

25. Scores of the different solutions in modeling R3

26. Requirements R3 Grades for the four solutions
Grade of the solution A 10 B 20 C 25 D

27. Correct Solution for requirements R1+R2+R3
(1,1)
(1,n) in
Parking
Code
Longitude &
Latitude
Address
Name
# of locations
# numeric code
Type of bike
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,1) On
(1,n)
State
Bike
Code
Date of purchase
(1,n)
Assisted
make
Normal

28. Requirements R4

29. Requirements R4
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type.
R2 - Each bike is identified by a numeric code, and a date of purchase; assisted bikes have a make, that may change among bikes (we do not represent the makes of normal bikes).
R3 - When bikes are not used, they are parked in locations of parking lots. As a consequence, for each bike and for each minute in the year (e.g. minute 34 of hour 10 a.m. of march 7th) we want to represent the state of the bike, namely if it is parked or it is in motion. Furthermore, for each minute in the year and each location in a parking lot, we want to represent, separately, which bike is possibly parked in the location (e.g. in minute 29 of hour 11 a.m. of march 21th bike 73 is parked in location 15 of parking lot 28, while in the same minute bike 130 is parked in location 6 of parking lot 112). Of course, if in a given minute a bike is in motion, the corresponding location in a parking lot does not exist, and, therefore, will not be represented. It is strongly recommended to represent the concept of minute with an Entity.
R4 – In order to use bikes, users have to register themselves. A registered user is characterized by an identifier (e.g. a fiscal code, or a social security number), a progressive numeric code (first person registered, second person registered, etc.) a name, a surname, date of birth, municipality of birth, with code, name of municipality and region (we assume that municipalities are located in regions).

30. Solution A Solution B Solution C Person Person Munici- pality Munici-
Code
Name
Region
Born in
Person Id
Numeric Code
First Name
Last Name
(1,1)
Munici-
pality
Solution A
(1,n)
Code
Name
Region
Born in
Registered
Person Id
First Name
Last Name
(1,1)
Munici-
pality
Numeric Code
Solution B
(1,n)
Code
Name
Region
Born in
Person Id
Numeric Code
First Name
Last Name
(1,1)
Munici-
pality
Solution C

31. Solution D Solution E Person Person Munici- pality Region Id
Numeric Code
First Name
Last Name
Code of Municipality
Name of Municipality
Region
Solution D
(1,n)
Code
Name
Born in
Person Id
Numeric Code
First Name
Last Name
(1,1)
Munici-
pality
Region
Located in
Solution E

32. Requirements R4 Grades for the five solutions
Grade of the solution A 12 B 9 C 15 D E 8

33. Correct solution for requirements R1+R2+R3+R4
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n) on
(1,n)
(1,n)
State
picks up
Bike
Code
Date of purchase
(1,n)
returns
(1,n)
(1,1)
Assisted
make
concerns Id
Numeric Code
First Name
Last Name
Normal
(1,n)
(1,1)
(1,1)
Person
Refers to
Event
# numeric code
Period of time
(1,1)
(1,n)
(1,1)
Born in
(1,n)
Munici-
pality
Code
Name
Region

34. Requirements R5

35. Requirements R5
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type.
R2 - Each bike is identified by a numeric code, and a date of purchase; assisted bikes have a make, that may change among bikes (we do not represent the makes of normal bikes).
R3 - When bikes are not used, they are parked in locations of parking lots. As a consequence, for each bike and for each minute in the year (e.g. minute 34 of hour 10 a.m. of march 7th) we want to represent the state of the bike, namely if it is parked or it is in motion. Furthermore, for each minute in the year and each location in a parking lot, we want to represent, separately, which bike is possibly parked in the location (e.g. in minute 29 of hour 11 a.m. of march 21th bike 73 is parked in location 15 of parking lot 28, while in the same minute bike 130 is parked in location 6 of parking lot 112). Of course, if in a given minute a bike is in motion, the corresponding location in a parking lot does not exist, and, therefore, will not be represented. It is strongly recommended to represent the concept of minute with an Entity.
R4 – In order to use bikes, users have to register themselves. A registered user is characterized by an identifier (e.g. a fiscal code, or a social security number), a progressive numeric code (first person registered, second person registered, etc.) a name, a surname, date of birth, municipality of birth, with code, name of municipality and region (we assume that municipalities are located in regions).
R5 – Everytime a user picks up and subsequently returns a bike, such an event (pick up and return of a bike by a user) has to be recorded. The event is identified by a progressive number in the year (e.g. first event in 2015, second event in 2015, etc.) and duration (e.g. 12 minutes, 47 minutes); such duration has to be explicitely represented in the data base. The minute of pick up and the minute of return have to be associated to the event, besides, of course, the bike used and the user involved.

36. For Requirements R5 we give the correct solution

37. Solution A - 25 Location Parking Minute In 2015 Bike Assisted Normal
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n) on
(1,n)
(1,n)
State
picks up
Bike
Code
Date of purchase
(1,n)
returns
(1,n)
(1,1)
Assisted
make
concerns Id
Numeric Code
First Name
Last Name
Normal
(1,n)
(1,1)
(1,1)
Person
Refers to
Event
# numeric code
Period of time
(1,1)
(1,n)
(1,1)
Born in
(1,n)
Munici-
pality
Code
Name
Region

38. Question: which ones among the following solutions are correct?

39. Solution A - 25 Location Parking Minute In 2015 Bike Assisted Normal
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n) on
(1,n)
State
(1,n)
Bike
Code
Date of purchase
Picks up
(1,n)
(1,1)
Assisted
make
concerns Id
Numeric Code
First Name
Last Name
Normal
(1,n)
(1,1)
Person
Refers to
Event
# numeric code
Period of time
(1,1)
(1,n)
(1,1)
Born in
(1,n)
Munici-
pality
Code
Name
Region

40. Solution B Location Parking Minute In 2015 Bike Assisted Normal Person
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n) on
(1,n)
(1,n)
State
picks up
Bike
Code
Date of purchase
(1,n)
returns
(1,n)
(1,n)
Assisted
make
concerns Id
Numeric Code
First Name
Last Name
Normal
(1,n)
(1,n)
(1,n)
Person
Refers to
Event
# numeric code
Period of time
(1,1)
(1,n)
(1,1)
Born in
(1,n)
Munici-
pality
Code
Name
Region

41. Solution C
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute
Hour
Day
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n) on
(1,n)
(1,n)
State
Bike
Code
Date of purchase
Loan event
(1,n)
Progressive number
period
Assisted
make Id
Numeric Code
First Name
Last Name
Normal
(1,n)
Person
(1,n)
(1,1)
Remark
This is a serious mistake, since in the ER model relationships
correspond to functions whose domains consist in the
Entities involved; so, relationships do not have identifiers.
Born in
(1,n)
Munici-
pality
Code
Name
Region

42. Scores for Requirements R5 X means correct solution
Solution A
Solution B
Solution C
Score X 25 16 8

43. Correct solution for Requirements R1+R2+R3+R4+R5
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute &
Hour &
Day &
Month
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n) on
(1,n)
(1,n)
State
picks up
Bike
Code
Date of purchase
(1,n)
returns
(1,n)
(1,n)
Assisted
make
concerns Id
Numeric Code
First Name
Last Name
Normal
(1,n)
(1,n)
(1,n)
Person
Refers to
Event
# numeric code
Period of time
(1,1)
(1,n)
(1,1)
Born in
(1,n)
Munici-
pality
Code
Name
Region

44. Requirements R6

45. Requirements R6
R1 – A Municipality (e.g. the municipality of Milan, Italy) aims at managing in a given year (e.g. in 2018) a bike sharing service. The service is organized in terms of parking lots, each one identifed by a code, a longitude, a latitude, an address, a name (e.g. Piazzale Susa), and by a number of locations for bycicles. Each location is identified by a progressive number in the parking and from the type of bike that can be hosted in the location, namely a. normal or b. assisted (namely, equipped with an electric motor). We assume that in a specific location of a parking lot it is always parked a bike of a given type.
R2 - Each bike is identified by a numeric code, and a date of purchase; assisted bikes have a make, that may change among bikes (we do not represent the makes of normal bikes).
R3 - When bikes are not used, they are parked in locations of parking lots. As a consequence, for each bike and for each minute in the year (e.g. minute 34 of hour 10 a.m. of march 7th) we want to represent the state of the bike, namely if it is parked or it is in motion. Furthermore, for each minute in the year and each location in a parking lot, we want to represent, separately, which bike is possibly parked in the location (e.g. in minute 29 of hour 11 a.m. of march 21th bike 73 is parked in location 15 of parking lot 28, while in the same minute bike 130 is parked in location 6 of parking lot 112). Of course, if in a given minute a bike is in motion, the corresponding location in a parking lot does not exist, and, therefore, will not be represented. It is strongly recommended to represent the concept of minute with an Entity.
R4 – In order to use bikes, users have to register themselves. A registered user is characterized by an identifier (e.g. a fiscal code, or a social security number), a progressive numeric code (first person registered, second person registered, etc.) a name, a surname, date of birth, municipality of birth, with code, name of municipality and region (we assume that municipalities are located in regions).
R5 – Everytime a user picks up and subsequently returns a bike, such an event (pick up and return of a bike by a user) has to be recorded. The event is identified by a progressive number in the year (e.g. first event in 2015, second event in 2015, etc.) and duration (e.g. 12 minutes, 47 minutes); such duration has to be explicitely represented in the data base. The minute of pick up and the minute of return have to be associated to the event, besides, of course, the bike used and the user involved.
R6 – One or more credit cards are associated to users, with type (e.g. Visa, Diners), progressive code in the card type, and daily maximum amount of withdrawal (that depends on the card and on the person).

46. Solution A Credit Card Person Type & Code (1,1) has Id Numeric Code
First Name
Last Name
(1,n)
Person
Maximum am.
of withdrawal

47. Solution B Credit Card Person Type Code (1,1) has Id Numeric Code
First Name
Last Name
(1,n)
Person
maximum amount
of withdrawal

48. Solution C Credit Card Person Type & Code (1,1) has maximum amount
of withdrawal Id
Numeric Code
First Name
Last Name
(1,n)
Person

49. Solution D Credit Card Person Type & Code (1,1) has maximum amount
of withdrawal Id
Numeric Code
First Name
Last Name
(1,1)
Person

50. Solution E Credit Card Person Type & Code Maximum am. of withdrawal
(1,1)
has Id
Numeric Code
First Name
Last Name
(1,n)
Person

51. Solution F Credit Card Person Type Code (1,1) has maximum amount
of withdrawal Id
Numeric Code
First Name
Last Name
(1,1)
Person

52. Solution G Credit Card Person Type Code maximum amount of withdrawal
(1,1)
has Id
Numeric Code
First Name
Last Name
(1,n)
Person

53. Solution H Credit Card Person Type Code maximum amount of withdrawal
(1,1)
has Id
Numeric Code
First Name
Last Name
(1,1)
Person

54. Requirements R6 Grades for the correct solution
Grade of the correct solution A 6 B 3 C 10 D E F G

55. Final Schema

56. Final correct solution
(1,1)
(1,n) in
Parking
# numeric code
Type of bike
Code
Longitude &
Latitude
Address
Name
# of locations
Location
Minute
Hour
Day
Month
Type &
Code
Credit
Card
Minute
In 2015
(1,n)
(1,n)
Parked in
(1,n)
(1,n)
(1,1) on
(1,n)
(1,n)
State
picks up
Code
Date of purchase
(1,n)
Bike
has
maximum amount
of withdrawal
returns
(1,n)
concerns
(1,1) Id
Numeric Code
First Name
Last Name
Assisted
(1,1)
Normal
make
(1,n)
(1,1)
(1,1)
Person
Refers to
Event
# numeric code
Period of time
(1,1)
(1,n)
(1,1)
Born in
(1,n)
Munici-
pality
Code
Name
Region