7. A3:
We have to consider the following problems :
not interpreted data
Mass of data (Non structured data)
I do not like the data
Biased data
Wrong data
Not accurate
Imprecise - Interpreted in many meaning
7
8. For the above reasons and others we have to make so many
considerations and good knowledge of how to deal with data.
The notion of dealing with data is called database; It includes:
DB design
DB Modeling
DB Redesign
Components of DB
Relational concept of DB
Normalization of DB
Single access to DB
Multi-user access DB
Application on Db (VB, JAVA, XML, ASP, ..)
8
9. The new trend of DB in the age of internet
Internet changed DB strategy from just publishing facts
to interaction between DBs and users in dynamic way
This new trajectory of DB makes people with this field
one of the most wanted worker in business
9
10. WHY solid and good DB ?
let us study the following DB:
Rent Company List
Contractor Equipment Phone $ rate/day Start date End date $charge and so on
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
JDS N 666 33 11/02/04 1/9/04 333$
OZ opics H 777 55 11/02/04 1/9/04 333$
H & C Comp B 222 11 11/11/04 12/12/04 444$ ….
H & C Comp C 222 11 11/11/04 12/12/04 444$ ….
H & C Comp D 222 11 11/11/04 12/12/04 444$ ….
Mitel F 555 12 11/02/04 1/9/04 333$
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
…..
……
Q4: Find out the problems from the above DB – table?
The problems justify the need for good DB strategies and solid design
procedures
10
11. Problem-1:
Rent Company List
Contractor Equipment Phone $ rate/day Start date End date $charge and so on
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
JDS N 666 33 11/02/04 1/9/04 333$
OZ opics H 777 55 11/02/04 1/9/04 333$
H & C Comp B 222 11 11/11/04 12/12/04 444$ ….
H & C Comp C 222 11 11/11/04 12/12/04 444$ ….
H & C Comp D 222 11 11/11/04 12/12/04 444$ ….
Mitel F 555 12 11/02/04 1/9/04 333$
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
…..
If there is change in phone number field for the H & C company, we have to
search all fields and change them one by one.
If the list contains 10 000 rows then 10 000 rows must be searched.
LENGTHY AND TEDIOUS PROCEDURE as well as possibility of making
error
If you forgot to update one or more rows of H&C company THEN you will be
stack in the problem of DATA INCONSISTENCY,
GOOD DB DESIGN must eliminate the occurrence of INCONSISTENCY in
the Data
11
12. Problem-2:
Rent Company List
Contractor Equipment Phone $ rate/day Start date End date $charge and so on
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
JDS N 666 33 11/02/04 1/9/04 333$
OZ opics H 777 55 11/02/04 1/9/04 333$
H & C Comp B 222 11 11/11/04 12/12/04 444$ ….
H & C Comp C 222 11 11/11/04 12/12/04 444$ ….
H & C Comp D 222 11 11/11/04 12/12/04 444$ ….
Mitel F 555 12 11/02/04 1/9/04 333$
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
…..
……
If the company H&C is permanent client of the Rental company, i.e. in one
year they have at least 1000 events or more THEN you have to repeat the
common fields (such as Address, Tel No) 1000 times; again LENGTHY
PROCEDUE AND MORE SPACE NEEDED
12
13. Problem 3 - 5
If the rental company uses PC for its data, then they
stack with problem of memory capacity.
Good DB designer must handle this problem by
eliminating the redundancy
Redundancy elimination in the DB will save time in
the search & transaction processes.
13
14. Problem 6:
Rent Company List
Contractor Equipment Phone $ rate/day Start date End date $charge and so on
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
JDS N 666 33 11/02/04 1/9/04 333$
OZ opics H 777 55 11/02/04 1/9/04 333$
H & C Comp B 222 11 11/11/04 12/12/04 444$ ….
H & C Comp C 222 11 11/11/04 12/12/04 444$ ….
H & C Comp D 222 11 11/11/04 12/12/04 444$ ….
Mitel F 555 12 11/02/04 1/9/04 333$
H & C Comp A 222 11 11/11/04 12/12/04 444$ ….
…..
……
If the client Mitel changed their mind and cancel the rental order
THEN the DB designer deletes the row of Mitel client this will cause lost of
data which might be needed for future events.
Good DB designer must think of such problems.
14
15. Problems could be more if you are using shared DB:
Just imagine if the data is shared by many users in the company ,
i.e. on different PCs
Then any change in the phone number by one user cause to
inconsistency, because other users still have the same old not
updated number
OR the DB administrator has to walk around the PC’s and update
the phone number NOT PRACTICAL – TIME CONSUNING
15
16. Other problems
Accounting want to keep track of the status of invoices
Sales want to keep track of contract approval
Customer support want to know which , where when problems
occurred to deliver an order in time (a sort of SCM)
job privacy (i.e. no other department see what they are doing)
Power failure cause to damage or lost of DB
Good pack up system
HENCE the need of security and privacy and DB Integrity.
16
17. The Characteristics of Databases
• The purpose of a database is to help people
track things of interest to them
• Data is stored in tables, which have rows and
columns like a spreadsheet. A database may
have multiple tables, where each table stores
data about a different thing
• Each row in a table stores data about an
occurrence or instance of the thing of interest
• A database stores data and relationships
17
20. Naming Conventions in this Textbook
• Table Names are written with all capital
letters:
– STUDENT, CLASS, GRADE
• Column names are written with an initial
capital letter, and compound names are
written with a capital letter on each word:
– Term, Section, ClassNumber, StudentName
20
21. Databases Create Information
• Data = Recorded facts and figures
• Information = Knowledge derived from
data
• Databases record data, but they do so in
such a way that we can produce
information from the data
– The data on STUDENTs, CLASSes and
GRADEs could produce information about
each student’s GPA
21
22. Database Examples
• Types of DB
• Personal database
– 1 user; < 10 MB
• Workgroup database
– < 25 users; < 100 MB
• Organizational database
– Hundreds to thousands users
– >1 Trillion bytes, possibly several databases
22
24. Microsoft Access
• Microsoft Access is a low-end product intended
for individual users and small workgroups
• MS Access tries to hide much of the underlying
database technology from the user
• A good strategy for beginners, but not for
database professionals
• NOTE: MS Access is discussed in detail in
Appendix A
24
26. Applications, the DBMS and SQL
• Applications are the computer programs that
users work with
• The Database Management System (DBMS)
creates, processes and administers databases
• Structured Query Language (SQL) is an
internationally recognized standard database
language that is used by all commercial DBMSs
26
28. Prominent DBMS Products
• Microsoft Access
• Microsoft SQL Server
– New: Microsoft SQL Server Express
• IBM DB2
• Oracle Corporation ORACLE
• And don’t overlook MySQL
28
34. Database Design from New
Systems Development
Entity-Relationship data modeling is covered in Chapter Five, and data model
transformations to database designs are covered in Chapter Six
34
35. Database Design from Database
Redesign
Database redesign is
covered in Chapter
Eight, after coverage of
SQL in Chapter Seven
35
