The document discusses basic database concepts such as what a database is, examples of databases, the basic components of databases including fields, records, tables, and how they relate, as well as the differences between a standard database and a relational database, and how data is added and validated in a database.

1. Basic Databases Concepts
By Odaly Fernandez

2. What is a database
 A database is any collection of information
(data).
 This collection represents part of the real
world.
 The data is organized in some manner so
that the information contained within the
database can be easily retrieved.

3. Examples of database
 Phone books
 Library
 School
 Search engines

4. Basic Database Concepts
 Field: a single piece of information
 Record: a collection of related fields
 Table: a collection of related records
 Database: a collection of tables

5. Difference between a database and a
relational database
 The difference is in the way the tables are
constructed.

6. Database
EMPLOYEE table
Name Employee Number Hire Date
Bill White 1122 1/1/2001
Ron Smith 2387 27/9/2001
Greg King 4456 24/8/1999
CUSTOMER table
Name Address Phone
Lyons 123 A Street 916-444-55
Dennys 435 Elm Street 916-478-23
IHOP 654 17th Av. 916-458-77
ORDERS table
Customer Name Order Number Cost
Lyons 101 23.78 €
Lyons 145 100.25 €
IHOP 152 54.89 €

7. Relational database
EMPLOYEE table
EmployeeID Name Hire Date
1122 Bill White 1/1/2001
2387 Ron Smith 27/9/2001
4456 Greg King 24/8/1999
CUSTOMER table
CustomerID Name Address Phone
100 Lyons 123 A Street 916-444-55
101 Dennys 435 Elm Street 916-478-23
102 IHOP 654 17th Av. 916-458-77
ORDERS table
Order Number Customer Number SalesID Cost
101 100 1122 23.78 €
145 100 2387 100.25 €
152 102 2387 54.89 €

8. Database Management System (DBMS)
 Software that allows users to create,
maintain, and query your data in the related
tables
 Examples: MS Access, Oracle, FoxPro,
MySql

9. Primary and foreign keys
 Primary Key, a value that is unique to each
record
 Foreign Key, a primary key of one table
included in another table. Link tables to each
other.
 Find the PK and FK on the last relational
database example.

10. Referential Integrity
DEPARTMENT
 Referential integrity is a DID DName
database concept that 13 Marketing
ensures that relationships
14 Accounts
between tables remain
consistent. 15 Personnel
 What happens if: EMPLOYEE
 Marketing’s DID is changed
EID EName DID
to 16 in DEPARTMENT?
 The entry for Accounts is 1515 John Smith 13
deleted from 1600 Mary Brown 14
DEPARTMENT?
1717 Mark Jones 13
1800 Jane Smith 13

11. Types of relationships
Example:
In a College database we might have Students,
Subjects, and Teachers, who are tutors at the
same time. Students might have attributes
such as their ID, Name, and could have
relationships with Subjects and Tutors.

12. Types of relationships
 One to one: each teacher has a unique office.
 One to many: a teacher may tutor many students, but each
student has just one tutor.
 Many to many: each student takes several subjects, and each
subject is taken by several students.
Exercise:
1. In the database Employee-Department, what type of
relationship do you find?
More examples:
1. In our database we are going to add Projects (new table). A
project can have many employees working on it. And, an
employee can work on many projects.
2. A manager manages one department; a department has only
one manager.

13. Types of relationships
 In a database we store information about
books, the authors, the category of the
books, and the publishers.
 A book can have more than one author.
 A book can be of more than one category.
 A publisher publishes many books. A book is
published only for one publisher.
 What types of relationships do we have here?

14. Designing a database structure
 As you are gathering information in the
requirements phase, you should be thinking
about these items:
 Identify all of the fields you are going to need
and ways to organize the related fields into
tables
 Determine or build a primary key for each
table if needed

15. Designing a database structure
 Compare the two tables below. You will see situations that you
want to avoid:
1) Avoid data redundancy.
2) If you can avoid data redundancy, you can avoid data
mistakes. Look at the customer name for customer #635 in both
tables. Two different spellings. Which one is correct?
3) Notice that there are two different customers in the Orders
table that have the same customer number (#104). If your billing
system uses the customer number to drive it, who’s going to get
the bill?
4) Notice that some of the customers in the Orders table aren’t
even listed in the Customer table. Will these customers ever get
a bill?

16. CUSTOMER table
CustID Name Address Phone City State
104 Meadows Restaurant Pond Hill Rd 313-792 Monroe Mi
128 Grand River Restaurant 37 Queue Av. 313-729 Lacota MI
163 Bentham’s Restaurant 1366 36th St 517-792 Monroe MI
635 Oaks Restaurant 3300 West Russell St 419-336 Maumee OH
741 Prime Cut Steakhouse 2819 East 10th St 219-336 Mishawalka IN
779 Gateway Lounge 3408 Gateway B1 419-361 Sylvania OH
ORDERS table
OrdID CustID Name Billing Date Invoice Amount
202 104 Meadows Restaurant 15/1/12 1280.50
226 635 Oakes Restaurant 15/1/12 1939.00
231 779 Gateway Lounge 15/1/12 1392.50
309 741 Prime Cut Steakhouse 15/2/12 1928.00
313 104 Stokes Inn 15/2/12 1545.00
377 128 Grand River Restaurant 15/3/12 562.00
359 635 Raks Restaurant 15/3/12 1939.00
373 779 Gateway Lounge 15/3/12 1178.00

17. Designing a database structure
A database is to be made to store information
about a catalogue of CDs. Information to be
stored about each CD includes their titles,
prices, and genre. This catalogue will take
into account only the “Rock”, “Pop”, and
“Rap” genre. Each CD will also have an artist,
and each artist may produce several CDs.
Artists have names associated with them.

18. Designing a database structure
 Identify tables, fields, and relationships from
the problem description.
 How do I find tables and fields?
 Tables and fields are often represented by
nouns in the description, so possible tables
from the CD problem description include
database, catalogue, cd, title (of CD), price,
genre, names. Some of these might not be
needed, and there may be others

19. Designing a database structure
 How do I tell the difference between a
table and a field?
 Field values are atomic, so fields can't have
smaller parts or be groups of things.
 Fields can't participate in relationships.
 Fields have a single value (a string, a
number, etc), whereas tables have complex
values (groups of fields generally).

20. Designing a database structure
 How do I find potential relationships
between tables?
 Relationships are often verbs or phrases that
link two tables in the problem description. For
example, if we have identified the tables CD
and artist, then a relationship between them
is described by the sentence "Each CD will
also have an artist, and each artist may
produce several CDs."

21. Designing a database structure
 How do I determine the type of relationship?
 Sometimes this is apparent from the description. For
example the sentence "Each CD will also have an
artist, and each artist may produce several CDs"
indicates that there is a one-to-many relationship
between artists and CDs - each artist is related to
many CDs, but each CD is related to just one artist.
 Sometimes it is less clear, and you need to think
about what situations are possible (not just likely).
This often involves detailed knowledge of the
problem, which means that making the right
decision helps to make the database represent this
knowledge.

22. Designing a database structure
So which are our tables?
Which fields should be primary key?
What relationships will be needed?
What data type should you use for each field?
ARTIST table CD table
artID cdID
artName artID
cdTitle
cdPrice
cdGenre

23. Adding information to the database
 Suppose we want to add the following CDs to the
database:
Artist Title Genre Price
Stellar Mix Rock 9.99
Stellar Magic Lines Rock 11.99
Spiritualized Amazing Grace Pop 9.99
The Feelers Supersystem Rock 11.99
Minuet The 88 Electronica 12.99
The Feelers Communicate Rock 9.99
Gang Starr Daily Operation Rap 10.99

24. Adding information to the database
 Each CD is going to require two entries - one in the
CD table, and one in the Artist. However, we don't
want to put each artist in more than once, and we
need to know the artist's ID before we can insert the
CD. This means that there are three stages to
inserting a CD:
 Check to see if there is an entry for the artist
involved
 If there is, get their artID, if not make a new entry
with a new artID
 Make an entry in the CD table with the artID from
step 2

25. Validation rules
 Range check
 Look-up check
 Format check
 Length check: passwords
 Type check

26. Data verification
 There are two main methods of verification:
 Double entry - entering the data twice and
comparing the two copies.
 Proofreading data - this method involves
someone checking the data entered against
the original document.