1. IST 210: Organization of Data
Database Design I
IST 210: Organization of Data

2. YOUR JOB! User requirement A database
IST210
I want a database to maintain departments in my company. Store information about my employees, their projects and assignments. I want ….
User requirement
$$$
Data Modeling
(Ch.4)
YOUR JOB!
Database Design (Ch.5)
A database

3. Two-Step Approach: Step 1
IST210
Two-Step Approach: Step 1
Data Modeling
(Ch.4)
Database Design (Ch.5)
Input: User requirement; Output: E-R Diagram
Use Entity-Relationship Diagram (E-R Diagram) to capture all user requirements

4. Two-Step Approach: Step 2
IST210
Two-Step Approach: Step 2
Data Modeling
(Ch.4)
Database Design (Ch.5)
Input: E-R diagram; Output: A database
Transferring a data model to a relational database
Entities  Relations
Relationships  Foreign keys and extra

5. Data Model (E-R Diagram)  Relational Model (Tables)
IST210
Chapter Key Objective
Data Model (E-R Diagram)  Relational Model (Tables)
Entity  Table
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
Relationship  Foreign key or a new table
Determined by the maximal cardinality
Specify the attribute properties
Data type
Key
Required
Determined by the minimal cardinality
Remarks

6. E-R Diagram  Tables Entity  Table Entity name  Table name
IST210
E-R Diagram  Tables
Entity  Table
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
Relationship  Foreign key or a new table
Specify the attribute properties

7. Example EMPLOYEE LOCKER EmployeeID LockerID Name LockerRoom
IST210
Example
EMPLOYEE
LOCKER
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
EmployeeID
LockerID
Name
OfficeNumber
OfficePhone
LockerRoom
LockerSize
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize)
*primary key: use underline

8. E-R Diagram  Tables Entity  Table Entity name  Table name
IST210
E-R Diagram  Tables
Entity  Table
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
Relationship  Foreign key or a new table
Determined by the maximal cardinality
Specify the attribute properties

9. Maximal Cardinality 1:1 (one-to-one) Relationship
IST210
Maximal Cardinality
1:1 (one-to-one) Relationship
1:N (one-to-many) Relationship
N:M (many-to-many) Relationship
Entity A
Entity B
Entity A
Entity B
Entity A
Entity B

10. 1:1 Relationship EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
IST210
1:1 Relationship
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE
LOCKER
Employee ID
Name
Office
Number
Phone 4
Tom
281
9182
Locker ID
Room
Size 1 #2 10 5
Relationship is not captured yet!
Add foreign key ?

11. Employee 4 owns locker 1; locker 1 belongs to employee 4. Option A
IST210
Employee 4 owns locker 1; locker 1 belongs to employee 4.
Option A
EMPLOYEE
LOCKER
Locker ID
Room
Size 1 #2 10 5
Employee ID
Name
Office
Number
Phone
Locker ID 4
Tom
281
9182 1
Option B
EMPLOYEE
LOCKER
Locker ID
Room
Size
EmployeeID 1 #2 10 4 5
Employee ID
Name
Office
Number
Phone 4
Tom
281
9182
Option C
EMPLOYEE
LOCKER
Locker ID
Room
Size
EmployeeID 1 #2 10 4 5
Employee ID
Name
Office
Number
Phone
Locker ID 4
Tom
281
9182 1

12. 1:1 Relationship *foreign key: italic
IST210
1:1 Relationship
*foreign key: italic
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
Option A
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize, EmployeeID)
Option B
Both options are correct. Option A is preferred.
If choosing Option A, since every employee has one locker, LockerID must have a value in EMPLOYEE table.
If choosing Option B, since some lockers does not belong to anyone, EmployeeID will be NULL value for some lockers and it takes extra space. (See the previous slide, Option B needs one more cell.)

13. IST210
1:1 Relationship
The maximum cardinality determines how a relationship is represented
1:1 relationship
The key from one relation is placed in the other as a foreign key
It does not matter which table receives the foreign key
We prefer the option taking less space

14. 1:N Relationship EMPLOYEE LOCKER EmployeeID LockerID Name OfficeNumber
IST210
1:N Relationship
EMPLOYEE
LOCKER
EmployeeID
LockerID
Name
OfficeNumber
OfficePhone
LockerRoom
LockerSize
Assume one-to-many relationship
EMPLOYEE
LOCKER
Employee ID
Last
Name
First
Office
Number
Phone 4
Green
Tom
281
9182
Locker ID
Room
Size 1 #2 10 5
Relationship is not captured yet!
Add foreign key ?

15. Employee 4 owns locker 1 and 5. Option A EMPLOYEE LOCKER
IST210
Employee 4 owns locker 1 and 5.
Option A
EMPLOYEE
LOCKER
Locker ID
Room
Size 1 #2 10 5
Employee ID
Name
Office
Number
Phone
Locker ID 4
Tom
281
9182
1, 5
Option B
EMPLOYEE
LOCKER
Locker ID
Room
Size
EmployeeID 1 #2 10 4 5
Employee ID
Name
Office
Number
Phone 4
Tom
281
9182
Option C
EMPLOYEE
LOCKER
EmployeeID
Name
Office
Number
Phone
Locker ID 4
Tom
281
9182
1, 5
Locker ID
Room
Size
EmployeeID 1 #2 10 4 5

16. 1:N Relationship EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
IST210
1:N Relationship
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize, EmployeeID)

17. IST210
1:N Relationship
Like a 1:1 relationship, a 1:N relationship is saved by placing the key from one table into another as a foreign key
However, in a 1:N the foreign key always goes into the many-side of the relationship
The 1 side is called the parent
The N side is called the child

18. N:M Relationship EMPLOYEE LOCKER EmployeeID LockerID Name OfficeNumber
IST210
N:M Relationship
EMPLOYEE
LOCKER
EmployeeID
LockerID
Name
OfficeNumber
OfficePhone
LockerRoom
LockerSize
Assume many-to-many relationship
EMPLOYEE
LOCKER
Employee ID
Name
Office
Number
Phone 4
Tom
281
9182 10
John
777
1829
Locker ID
Room
Size 1 #2 10 5
Relationship is not captured yet!
Add foreign key ?

19. Employee 4 owns locker 1 and 5. Employee 10 owns locker 1.
IST210
Employee 4 owns locker 1 and 5. Employee 10 owns locker 1.
Option A
EMPLOYEE
LOCKER
Employee ID
Name
Office
Number
Phone
Locker ID 4
Tom
281
9182
1, 5 10
John
777
1829 1
Locker
Number
Room
Size 1 #2 10 5
Option B
EMPLOYEE
LOCKER
Locker ID
Room
Size
EmployeeID 1 #2 10
4, 10 5 4
Employee ID
Name
Office
Number
Phone 4
Tom
281
9182 10
John
777
1829

20. Employee 4 owns locker 1 and 5. Employee 10 owns locker 1.
IST210
Employee 4 owns locker 1 and 5. Employee 10 owns locker 1.
EMPLOYEE
LOCKER
Employee ID
Name
Office
Number
Phone 4
Tom
281
9182 10
John
777
1829
Locker ID
Room
Size 1 #2 10 5
ASSIGNMENT
Employee ID
Locker 4 1 5 10
NOT SIMPLY ADDING FOREIGN KEYS! CREATE ANOTHER TABLE!

21. IST210
N:M Relationship
EMPLOYEE(EmployeeID, LastName, FirstName, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize)
ASSIGNMENT(EmployeeID, LockerID)
Note: EmployeeID and LockerID are both primary keys and foreign keys in ASSIGNMENT table

22. IST210
N:M Relationship
To represent a N:M relationship in relational design, a new table must be created.
This table is called an intersection table
An intersection table has a composite key consisting of the keys from each of the tables that it connects

23. Relationship Summary 1:1  add a foreign key to either table
IST210
Relationship Summary
1:1  add a foreign key to either table
(preferred)
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize) or
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize, EmployeeID)
1:N  add a foreign key to the many-side table
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize, EmployeeID)
N:M  add an intersection table
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone)
LOCKER(LockerID, LockerRoom, LockerSize)
ASSIGNMENT(EmployeeID, LockerID)

24. In-class Exercise 1 Transform this diagram into tables PARKING USER
IST210
In-class Exercise 1
Transform this diagram into tables
PARKING
USER
SpotID
UserID
Location
MonthlyCost
Name

25. In-class Exercise 1 Transform this diagram into tables PARKING USER
IST210
In-class Exercise 1
Transform this diagram into tables
PARKING
USER
SpotID
UserID
Location
MonthlyCost
Name
PARKING(SpotID, Location, MonthlyCost)
USER(UserID, Name, , SpotID)

26. In-class Exercise 1: Notes
IST210
In-class Exercise 1: Notes
PARKING(SpotID, Location, MonthlyCost)
USER(UserID, Name, , SpotID)
PARKING(SpotID, Location, MonthlyCost, UserID)
USER(UserID, Name, )
Note: both options are correct, but the first one is preferred because of the minimal cardinality of SpotID is mandatory.

27. In-class Exercise 2 Transform this diagram into tables APARTMENT
IST210
In-class Exercise 2
Transform this diagram into tables
BuildingNameApartmentID
NumberOfBed
NumberOfBath
Rent
BuildingName
Address
APARTMENT
BUILDING

28. In-class Exercise 2 Transform this diagram into tables
IST210
In-class Exercise 2
Transform this diagram into tables
BUILDING(BuildingName, Address)
APARTMENT(BuildingName, ApartmentID, NumberOfBedrooms, NumberofBaths, Rent)

29. In-class Exercise 2: Notes
IST210
In-class Exercise 2: Notes
BUILDING(BuildingName, Address)
APARTMENT(BuildingName, ApartmentID, NumberOfBedrooms, NumberofBaths, Rent)
Notes:
* A common mistake is making ApartmentID as the only primary key. (BuildingName, ApartmentID) should a composite key for APARTMENT
* Another common mistake is to create a duplicate attribute BuildingName in APARTMENT. Or forget to make BuildingName as the foreign key

30. In-class Exercise 3 Transform this diagram into tables STUDENT COURSE
IST210
In-class Exercise 3
Transform this diagram into tables
CourseID
CourseName
Instructor
StudentID
StudentName
COURSE
STUDENT

31. In-class Exercise 3 Transform this diagram into tables STUDENT COURSE
IST210
In-class Exercise 3
Transform this diagram into tables
CourseID
CourseName
Instructor
StudentID
StudentName
COURSE
STUDENT
STUDENT(StudentID, StudentName, )
COURSE(CourseID, CourseName, Instructor)
REGISTRATION(StudentID, CourseID)

32. In-class Exercise 3: Notes
IST210
In-class Exercise 3: Notes
STUDENT(StudentID, StudentName, )
COURSE(CourseID, CourseName, Instructor)
REGISTRATION(StudentID, CourseID)
Notes:
* In REGISTRATION table, StudetID and CourseID are both primary key and foreign key. So you should give both underline and italic (wave underline in hand-written format) to them.

33. E-R Diagram  Tables Entity  Table Entity name  Table name
IST210
E-R Diagram  Tables
Entity  Table
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
Relationship  Foreign key or a new table
Determined by the maximal cardinality
1:1  add a foreign key to either table
1:N  add a foreign key to the many-side table
N:M  add an intersection table
Specify the attribute properties

34. E-R Diagram  Tables Entity  Table Entity name  Table name
IST210
E-R Diagram  Tables
Entity  Table
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
Relationship  Foreign key or a new table
Determined by the maximal cardinality
Specify the attribute properties
Data type
Key
Required
Determined by the minimal cardinality
Remarks

35. Column Name Data Type Key Required Remarks EmployeeID Name
IST210
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE table
Column Name
Data Type
Key
Required
Remarks
EmployeeID
Name
OfficeNumber
OfficePhone
LockerID
LOCKER table
Column Name
Data Type
Key
Required
Remarks
LockerID
LockerRoom
LockerSize

36. Determine the data types based on the type of these attributes
IST210
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE table
Column Name
Data Type
EmployeeID
int
Name
char(50)
OfficeNumber
char(20)
OfficePhone
char(12)
LockerID
Data Type
Determine the data types based on the type of these attributes
Data types must be the types defined in SQL
Data type of a foreign key must be the same type as its referred primary key
LockerID in EMPLOYEE table must have the same data type as LockerID in LOCKER because LockerID is a foreign key in EMPLOYEE
LOCKER table
Column Name
Data Type
LockerID
int
LockerRoom
char(10)
LockerSize
float

37. Specify primary key and foreign key(s) in the table
IST210
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE table
Column Name
Key
EmployeeID
Primary key
Name
OfficeNumber
OfficePhone
LockerID
Foreign key
Key
Specify primary key and foreign key(s) in the table
LOCKER table
Column Name
Data Type
LockerID
Primary key
LockerRoom
LockerSize

38. Primary key must be required
IST210
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE table
Column Name
Required
EmployeeID
Yes
Name
OfficeNumber No
OfficePhone
LockerID
Required
Whether an attribute is required or not determines whether we allow NULL value for this attribute
Primary key must be required
Normal attributes are determined based on requirements or common sense
“not required” is preferred
Foreign key is determined by minimum cardinality
An employee must have at least one locker. So LockerID is required in EMPLOYEE
LOCKER table
Column Name
Required
LockerID
Yes
LockerRoom
LockerSize

39. Surrogate key: initial value = 1 Increment = 1 Name OfficeNumber
IST210
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE table
Column Name
Remarks
EmployeeID
Surrogate key: initial value = 1 Increment = 1
Name
OfficeNumber
OfficePhone
Format: ###-###-####
LockerID
Reference: LOCKER
Remarks
If a primary key is a surrogate key, specify the initial value and increment
If an attribute is a foreign key, specify which table it refers to
If an attribute has a required format, specify the format
If an attribute has a default value, specify the value
LOCKER table
Column Name
Remarks
LockerID
Surrogate key: initial value = 1 Increment = 1
LockerRoom
LockerSize
Default value: 10

40. Now we complete converting an E-R diagram to tables
IST210
EMPLOYEE(EmployeeID, Name, OfficeNumber, OfficePhone, LockerID)
LOCKER(LockerID, LockerRoom, LockerSize)
EMPLOYEE table
LOCKER table
Column Name
Data Type
Key
Required
Remarks
EmployeeID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
Name
char(50)
OfficeNumber
char(20) No
OfficePhone
char(12)
Format: ###-###-####
LockerID
Foreign key
Reference: LOCKER
Column Name
Data Type
Key
Required
Remarks
LockerID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
LockerRoom
char(10)
LockerSize
float
Default value: 10
Now we complete converting an E-R diagram to tables
Next, we can use SQL to create a real database

41. In-class Exercise 1 PARKING(SpotID, Location, MonthlyCost)
IST210
In-class Exercise 1
PARKING(SpotID, Location, MonthlyCost)
USER(UserID, Name, , SpotID)

42. PARKING(SpotID, Location, MonthlyCost)
IST210
In-class Exercise 1
PARKING(SpotID, Location, MonthlyCost)
USER(UserID, Name, , SpotID)
PARKING table
Column Name
Data Type
Key
Required
Remarks
SpotID
Location
MonthlyCost
USER table
Column Name
Data Type
Key
Required
Remarks
UserID
Name
SpotID

43. PARKING(SpotID, Location, MonthlyCost)
IST210
PARKING(SpotID, Location, MonthlyCost)
USER(UserID, Name, , SpotID)
PARKING table
Column Name
Data Type
Key
Required
Remarks
SpotID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
Location
char(50)
MonthlyCost
Default: 50
USER table
Column Name
Data Type
Key
Required
Remarks
UserID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
Name
char(100)
char(50) No
SpotID
Foreign key
Reference: PARKING

44. Notes: See the red parts
IST210
PARKING(SpotID, Location, MonthlyCost)
USER(UserID, Name, , SpotID)
PARKING table
Column Name
Data Type
Key
Required
Remarks
SpotID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
Location
char(50)
MonthlyCost
Default: 50
USER table
Column Name
Data Type
Key
Required
Remarks
UserID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
Name
char(100)
char(50) No
SpotID
Foreign key
Reference: PARKING
Notes:
See the red parts
Char is not a data type, char(50) is a data type. If you use char, you need to specify the max length
When you can use other data types, do not use char. For example, it is better to use int for MonthlyCost instead of using char

45. In-class Exercise 2 Transform this diagram into tables
IST210
In-class Exercise 2
Transform this diagram into tables
BUILDING(BuildingName, Address)
APARTMENT(BuildingName, ApartmentID, NumberOfBedrooms, NumberofBaths, Rent)

46. In-class Exercise 2 BUILDING(BuildingName, Address)
IST210
BUILDING(BuildingName, Address)
APARTMENT(BuildingName, ApartmentID, NumberOfBedrooms, NumberofBaths, Rent)
BUILDING table
Column Name
Data Type
Key
Required
Remarks
BuildingName
Address
APARTMENT table
Column Name
Data Type
Key
Required
Remarks
BuildingName
ApartmentID
NumberOfBed
NumberOfBath
Rent

47. BUILDING(BuildingName, Address)
IST210
BUILDING(BuildingName, Address)
APARTMENT(BuildingName, ApartmentID, NumberOfBedrooms, NumberofBaths, Rent)
BUILDING table
Column Name
Data Type
Key
Required
Remarks
BuildingName
Char(20)
Primary key
Yes
Address
Char(100)
Format: street, city, state, zip code
APARTMENT table
Column Name
Data Type
Key
Required
Remarks
BuildingName
Char(20)
Primary key, foreign key
Yes
Reference: BUILDING
ApartmentID
int
Primary key
NumberOfBed
float
NumberOfBath
Rent

48. IST210
BUILDING table
Column Name
Data Type
Key
Required
Remarks
BuildingName
Char(20)
Primary key
Yes
Address
Char(100)
Format: street, city, state, zip code
APARTMENT table
Column Name
Data Type
Key
Required
Remarks
BuildingName
Char(20)
Primary key, foreign key
Yes
Reference: BUILDING
ApartmentID
int
Primary key
NumberOfBed
float
NumberOfBath
Rent
Notes:
ApartmentID should NOT be a surrogate key. In real scenarios, we are using some meaningful ApartmentIDs, such as 100 or 201 instead of a meaningless system-generated id.
Use float for #ofBed, #ofBath, and Rent. Because #ofBath could be 1.5 and rent could be $890.50, which are not integers.

49. In-class Exercise 3 Transform this diagram into tables
IST210
In-class Exercise 3
Transform this diagram into tables
STUDENT(StudentID, StudentName, )
COURSE(CourseID, CourseName, Instructor)
REGISTRATION(StudentID, CourseID)

50. In-class Exercise 3 STUDENT(StudentID, StudentName, Email)
IST210
STUDENT(StudentID, StudentName, )
COURSE(CourseID, CourseName, Instructor)
REGISTRATION(StudentID, CourseID)
STUDENT table
Column Name
Data Type
Key
Required
Remarks
StudentID
StudentName
COURSE table
Column Name
Data Type
Key
Required
Remarks
CourseID
CourseName
Instructor
REGISTRATION table
Column Name
Data Type
Key
Required
Remarks
StudentID
CourseID

51. STUDENT(StudentID, StudentName, Email)
IST210
STUDENT(StudentID, StudentName, )
COURSE(CourseID, CourseName, Instructor)
REGISTRATION(StudentID, CourseID)
STUDENT table
Column Name
Data Type
Key
Required
Remarks
StudentID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
StudentName
Char(100)
Char(50) No
COURSE table
Column Name
Data Type
Key
Required
Remarks
CourseID
Char(20)
Primary key
Yes
Format: DepartmentName + CourseNumber
CourseName
Char(50)
Instructor
Char(100) No
REGISTRATION table
Column Name
Data Type
Key
Required
Remarks
StudentID
int
Primary key, foreign key
Yes
Reference: STUDENT
CourseID
Char(20)
Reference: COURSE

52. IST210
STUDENT table
Column Name
Data Type
Key
Required
Remarks
StudentID
int
Primary key
Yes
Surrogate key: initial value = 1 Increment = 1
StudentName
Char(100)
Char(50) No
COURSE table
Column Name
Data Type
Key
Required
Remarks
CourseID
Char(20)
Primary key
Yes
Format: DepartmentName + CourseNumber
CourseName
Char(50)
Instructor
Char(100) No
REGISTRATION table
Column Name
Data Type
Key
Required
Remarks
StudentID
int
Primary key, foreign key
Yes
Reference: STUDENT
CourseID
Char(20)
Reference: COURSE
Notes:
A CourseID should not be integer, for example, “IST210” is a courseID. CourseName for IST210 is “Organization of the data”.

53. E-R Diagram  Tables Entity  Table Entity name  Table name
IST210
E-R Diagram  Tables
Entity  Table
Entity name  Table name
Identifier  Primary key
Attributes  Attributes
Relationship  Foreign key or a new table
Specify the attribute properties

54. IST210
Attendance check?