1. Databases

2. Learning Objectives: By the end of this topic you should be able to:
describe the terms used in a relational database
identify primary keys and foreign keys
define relationships between entities using an entity relationship diagram for a given scenario
Define

3. What is a database?
What information would you record about a customer of a supermarket?
What information would you record about a book in a library?

4. What is a database?
a collection of data organised into a structured format.

5. What is a database?
Surname: James
First name: Samantha
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
a collection of data organised into a structured format.

6. What is a database?
Surname: James
First name: Samantha
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
Surname: Brown
First name: David
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
a collection of data organised into a structured format.

7. What is a database?
Surname: James
First name: Samantha
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
Surname: Brown
First name: David
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
Surname: Lastler
First name: David
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
a collection of data organised into a structured format.

8. What is a database?
Surname: James
First name: Samantha
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
Surname: Brown
First name: David
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
Surname: Lastler
First name: David
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
Surname: Whitefield
First name: Nina
Date of Birth:
Address: 16 Poppy Close
Town: Southam
County: Warwickshire
a collection of data organised into a structured format.

9. Tables

10. Tables aka: an entity a collection of data about a certain ‘thing’
a collection of records in a relational database
tables contain:
rows (each row contains a record)
columns (each column is a field)
a relational database is made up of a number of tables
a library database will have tables for Books, Members, ….
the name of a table is usually capitalised:
CUSTOMER(CustomerID, Forename, Surname,……, …..)
Relationships

11. Records a record is a row in a database table,
contains all the data about a single item or event
a customer file record will store the data about a customer
records are made up of a number of fields
each record contains individual items of data (in fields)

12. Fields aka: an attribute an individual data item within a record
a column in a database record,
each record will be made up of a series of fields
e.g. name, address etc.
BOOK entity of a library will usually contain the attributes: ISBN, Title, AuthorForename, AuthorSurname, Publisher, …..

13. Primary Key every record in a table needs to be able to be identified
primary key is the field that identifies a record uniquely
e.g. account number, part number, membership number
hint: often has ID, Number, No, or Code at the end of the field name
often underlined
e.g. MEMBER(MemberID, Forename, Surname, TelNo, ….)
used to create a relationship between tables
used to prevent data duplication
Foreign Key

14. Standard Notation e.g. for a library database:
MEMBER(MemberID, Forename, Surname, ….)
BOOK(BookID, Title, Author ….)
LOANS(LoanNo, MemberID, BookID, DateOut, …)
Entities are written in capital letters
Attributes are written with an initial capital
Primary keys are underlined
or labelled PK
Foreign keys are overlined
for OCR board
or labelled FK

15. Databases
A database consists of a number of t*****.

16. Databases
A database consists of a number of tables.

17. Databases A database consists of a number of tables.
A table consists of a number of r******.

18. Databases A database consists of a number of tables.
A table consists of a number of records.

19. Databases A database consists of a number of tables.
A table consists of a number of records.
A record consists of a number of f*****.

20. Databases A database consists of a number of tables.
A table consists of a number of records.
A record consists of a number of fields.

21. Databases A database consists of a number of tables
A table consists of a number of records
A record consists of a number of fields
The most important field is the p****** k**.

22. Databases A database consists of a number of tables
A table consists of a number of records
A record consists of a number of fields
The most important field is the primary key.

23. Databases A database consists of a number of tables
A table consists of a number of records
A record consists of a number of fields
The most important field is the primary key
A primary key contains data u***** to a record.

24. Databases A database consists of a number of tables
A table consists of a number of records
A record consists of a number of fields
The most important field is the primary key
A primary key contains data unique to a record.
Foreign Key

25. Library Database
Members of a library are loaned books

26. Library Database
Members of a library are loaned books
Entities:

27. Library Database Members of a library are loaned books Entities:

28. Library Database Members of a library are loaned books Entities:

29. Library Database Members of a library are loaned books Entities:
LOANS
Relationships

30. Library Database Members of a library are loaned books Entities:
MEMBERS(MembersID, Forename, Surname, …...)
BOOKS
LOANS
Relationships

31. Library Database Members of a library are loaned books Entities:
MEMBERS(MembersID, Forename, Surname, …...)
BOOKS(BookID, ISBN, Title, Author, …..)
LOANS
Relationships

32. Library Database Members of a library are loaned books Entities:
MEMBERS(MembersID, Forename, Surname, …...)
BOOKS(BookID, ISBN, Title, Author, …..)
LOANS(LoanID,
Relationships

33. Library Database Members of a library are loaned books Entities:
MEMBERS(MembersID, Forename, Surname, …...)
BOOKS(BookID, ISBN, Title, Author, …..)
LOANS(LoanID, MembersID,
Relationships

34. Library Database Members of a library are loaned books Entities:
MEMBERS(MembersID, Forename, Surname, …...)
BOOKS(BookID, ISBN, Title, Author, …..)
LOANS(LoanID, MembersID, BookID,
Relationships

35. Library Database Members of a library are loaned books Entities:
MEMBERS(MembersID, Forename, Surname, …...)
BOOKS(BookID, ISBN, Title, Author, …..)
LOANS(LoanID, MembersID, BookID, LoanDate, …)
Relationships

36. Foreign Key used to link the tables in a relational database.
a field in one table that is also the primary key in another
often overlined (or labelled FK):
MEMBERS(MembersID, Forename, Surname, …...)
BOOK(BookID, ISBN, Title, Author, …..)
LOANS(LoanID, MembersID, BookID, LoanDate, ….)

37. Entity Relationship Diagrams
New slideshow: ERD
ERD

38. Driving School Database

39. Driving School Database
Customers

40. Driving School Database
Customers book

41. Driving School Database
Customers book lessons

42. Driving School Database
Customers book lessons in a

43. Driving School Database
Customers book lessons in a car

44. Driving School Database
Customers book lessons in a car with an

45. Driving School Database
Customers book lessons in a car with an instructor.

46. Driving School Database
Customers book lessons in a car with an instructor.
Entities:

47. Driving School Database
Customers book lessons in a car with an instructor.
Entities:
CUSTOMERS

48. Driving School Database
Customers book lessons in a car with an instructor.
Entities:
CUSTOMERS
LESSONS

49. Driving School Database
Customers book lessons in a car with an instructor.
Entities:
CUSTOMERS
LESSONS
CAR

50. Driving School Database
Customers book lessons in a car with an instructor.
Entities:
CUSTOMERS
LESSONS
CAR
INSTRUCTOR

51. Restaurant Database Customers make reservations.
Orders are made of menu items and are given to the waiter.
Entities:
CUSTOMERS
RESERVATION
ORDER
MENU_ITEMS
WAITER

52. Foreign Key used to link the tables in a relational database.
a field in one table that is also the primary key in another
often overlined:
MEMBER(MemberID, Forename, Surname, …...)
BOOK(BookID, ISBN, Title, …..)
LOANS(LoanID, MemberID, BookID, LoanDate, ….)

53. Relationships Members of a library are loaned books Entities: MEMBERS
LOANS

54. Relationships
MEMBERS

55. Relationships
MEMBERS
LOANS

56. Relationships
MEMBERS
LOANS

57. Relationships
MEMBERS
LOANS
BOOKS

58. Relationships
MEMBERS
LOANS
BOOKS

59. Relationships
MEMBERS
MemberID
LOANS
LoanID
BOOKS
BookID

60. Relationships
MEMBERS
MemberID
LOANS
LoanID
MemberID
BOOKS
BookID

61. Relationships MEMBERS LOANS BOOKS MemberID LoanID MemberID BookID

62. Relationships MEMBERS LOANS BOOKS MemberID Forename Surname PostCode
LoanID
MemberID
BookID
DateOut
BOOKS
BookID
Title
Author
ISBN

63. Relationships MEMBERS LOANS BOOKS
MemberID
Forename
Surname
PostCode
LOANS
LoanID
MemberID
BookID
DateOut
BOOKS
BookID
Title
Author
ISBN
MEMBERS(MemberID, Forename, Surname, PostCode)
BOOKS(BookID, Title, Author, ISBN)
LOANS(LoanID, MemberID, BookID, DateOut)
Relationships
Primary Key

64. Foreign Key used to link the tables in a relational database.
a field in one table that is also the primary key in another
often overlined:
MEMBER(MemberID, Forename, Surname, …...)
BOOK(BookID, ISBN, Title, …..)
LOANS(LoanID, MemberID, BookID, LoanDate, ….)

65. Relationships (SBD 2012)
Outlets have visits for different types of inspection
Entities:
OUTLET
INSPECTIONTYPES
INSPECTIONVISITS

66. Exam question:

67. Exam question:

68. Exam question:

69. Exam question:

70. Relationships

71. Relationships
A primary key is a ***** that contains a ****** item of **** that identifies a particular ******.

72. Relationships
A primary key is a ***** that contains a ****** item of **** that identifies a particular ******.
A foreign key is the ******* *** from another e***** and is used to l*** the t****s together forming a ************.

73. Relationships
the links between entities in a relational database:

74. Relationships
the links between entities in a relational database:

75. Relationships the links between entities in a relational database:
there are three degrees of relationship between entities:

76. Relationships the links between entities in a relational database:
there are three degrees of relationship between entities:
one-to-one,

77. Relationships the links between entities in a relational database:
there are three degrees of relationship between entities:
one-to-one,
one-to-many,

78. Relationships the links between entities in a relational database:
there are three degrees of relationship between entities:
one-to-one,
one-to-many,
many-to-many.

79. Relationships

80. One-to-One Relationship

81. One-to-Many Relationship

82. Many-to-Many Relationship

83. Many-to-Many Relationship
usually broken down into two 1:many relationships
using a link table

84. Many-to-Many Relationship

85. Exam question:
A company stores details of customers and bookings in a database.
Two of the entities in the database are CUSTOMER and BOOKING.
What is the relationship between CUSTOMER and BOOKING? [1]

86. Exam question:

87. Exam question:

88. Exam Question:
A company manufactures electronic tills for use in shops.
The company has decided to write a database to store information about its sales.
The entities that will be used in the database are:
CUSTOMER: A list of the customers that have purchased tills from them
TILL: A list of tills that are produced by the company
SALESPERSON: The member of the company who was responsible for the sale
ORDER: The details of the orders placed by the company
ORDER_LINES: The details of the individual tills that make up each order
Draw the Entity Relationship Diagram (ERD) making sure that the degree of each relationship is identified [6]

89. Relationships to link records in different tables
making sure data is not duplicated
by ensuring referential integrity
reduces storage space required
since data is not duplicated

90. Entity-Relationship diagrams
E-R diagram (ERD),

91. Entity-Relationship diagrams
E-R diagram (ERD),
a graphical representation of the entities and the relationships between them,

92. Entity-Relationship diagrams
E-R diagram (ERD),
a graphical representation of the entities and the relationships between them,
from Access

93. Entity-Relationship diagrams
E-R diagram (ERD),
a graphical representation of the entities and the relationships between them,
from Access
manually drawn
CUSTOMER
BOOKINGS
STAFF

94. Entity Relationship diagram
Members of a marching band who are loaned instruments and attend events:

95. Standard Notation Entities are written in capital letters
Attributes are written with an initial capital
Primary keys are underlined
or labelled PK
Foreign keys are overlined
for OCR board
or labelled FK

96. Standard Notation Entities are written in capital letters
Attributes are written with an initial capital
Primary keys are underlined
or labelled PK
Foreign keys are overlined
for OCR board
or labelled FK
e.g. for a library database:
MEMBER(MemberID, Forename, Surname, ….)
BOOK(BookID, Title, Author ….)
LOANS(LoanNo, MemberID, BookID, DateOut, …)

97. Referential Integrity
every foreign key must have a related primary key value
e.g. for a customer ID in a hire table there must be the same customer (ID) in the customer table
you can’t hire something to a non-existent customer!
if a customer record is deleted then all ‘hires’ by the deleted cusomer are removed.
ensures no redundant data is stored

98. Duplicate Data more than 1 copy of a data record
e.g. customer’s data entered & stored twice
data taking up more storage space than necessary
possible data inconsistency
2 different copies of the data

99. Entity Relationship Diagram (SBD 2012)