1. Agricultural to Industrial to Information Age
Data
Bits and Bytes
e.g
Information
organized and presented in a form suitable for decision making
e.g. (518)
Knowledge
Ref. Alvin Toffler (1980)
Data is raw, unsummarized and unanalyzed facts.
We are Data rich and Information poor 1

2. Desirable Attributes of Information
Shareable
Transportable
Secure
Accurate
Timely
Relevant
Readily accessed by more than one person at a time
Easily moved to a decision maker
Protected from unauthorized use and and destruction
Reliable, precise records
Current and up to date
Appropriate to the decision
information: Shareable, Transportable, NOT secure
Accurate, Timely & Relevant ?
Depends on situation

3. Where do companies get information from?
They buy it
Consultants, publications, news services etc.
They generate it
Computer systems (programs process data stored in databases)
Employees (apply experience and intelligence)
Who needs it?
Higher level managers need less detailed information
e.g.. I need your names
My chair needs only my class size
The president needs only growth trends
How is it stored?
Tape or disk 2

4. Where do we store Intangible Assets -- Information?
In people’s heads
On paper
In card-files
In computers
Computers are like intricate card files with better indexing
Information is the content, and the delivery mechanism is technology
e.g if a water utility company created the best pipes, taps and dams but when the customer turns it on, brown sludge comes out!!

5. Entities, Attributes, and Relationships
Entity – a person, place, thing, or event
Attribute – a property of an entity
For the entity “Person,” attributes could include eye color and height
Relationship – an association between entities
Publishers are related to the books they publish, and a book is related to its publisher
Weak or dependent entity (child) is existence-dependent on some other entity type (strong or parent)
E.g. next of kin is a weak entity (requires employee)
Attributes can be simple or composite (e.g. address)

6. Terminology Fields - attribute
Domain -Description of allowed values for an attribute
Records - logically connected set of one or more fields.
Files - collection of records
A field is some characteristic of the real-world object that is being modeled
A domain is the pool of potential values. The concept of a domain is actually too complex for most systems to support

7. History of Data Processing
Manual record-keeping
High labor costs and human errors
Data file – stores information on a single entity and the attributes of that entity
Database – a structure that can store information about multiple types of entities, the attributes of these entities, and the relationships among the entities
Manual record keeping works well if you only have to store and retrieve items, but breaks down if you want to cross-reference information.
File -based systems are more efficient but take a decentralized approach so a lot of data is duplicated. Each application program defines the physical structure and storage of the data file and records. 4

8. Limitations of File-Based Systems
Separation and Isolation of Data
Duplication of Data
Data dependence
Incompatibility of files
Fixed queries / proliferation of application programs / pressure on DP staff
1) Difficult to access data (need to synchronize the processing of two or more files)
2) Duplication wastes time and money with data entry and takes up computer storage space. Also could lead to inconsistencies.
3) For example, to change the size of a field in a file, need to write a new program to replace the original but also need to identify any other program that accesses that file and modify them, even if they do not use that particular field.
4) The structure of a file generated by COBOL is different from that of a file generated by a C program and so cannot process the files jointly
5) All queries and reports have to be written by an application programmer, so no ad hoc queries

9. Database A self-describing collection of integrated records
Properties of a Database:
It represents some aspect of the real world
It is a logically coherent collection of data with some inherent meaning
It is designed, built, and populated with data for a specific purpose
It has users and applications
A shared corporate resource that has minimum duplication
The description of the data is called a system catalog or data dictionary or meta-data. This provides program-data independence
If we add a field or create a file, existing applications are unaffected, but if we delete a field from a file that an application program uses, then that program must be modified. 6

10. Spreadsheet or Database?
Data size
Data storage format
Data structure
extent to which relationships among data items are fixed
Data sharing
Data control
degree of data input editing and validating
SS can handle about 5000 records, DB can effectively handle up to a million
DB can open, use and store files that are pictures, graphs, audio, video, spreadsheets and word documents
If relationships are static (use the data in the same way always) SS may be OK, but for dynamic queries, need DB.
Number of users who have access to data . If low (e.g if only for acctg dept) use SS, but if acctg, sales and inventory all query the data then it remains undisturbed in a DB.
Hi control in DB (e.g. sales data as opposed to forecasting estimates)

11. Static
Dynamic
Structure
Low
High
Low
High
Sharing
High
Low
High
Low
High
Low
High
Low
Control
Spreadsheet DB
Database
Either
SOLUTION

12. DBMS A software system that :
Enables users to define, create and maintain the database
Provides controlled access to this database
File processing systems support a limited schema through the creation of directory structures for files
They do not support a query language
They do not guarantee against data loss if it is not backed up
Do not support efficient access to data items whose location in a particular file is not known
When they allow concurrent access, they will not prevent two users from modifying the same file at the same time 11

13. DBMS components Machine Data Human Hardware Software Procedures People
Hardware: PC, mainframe or network of computers (e.g. client-server architecture)
Software consists of the DBMS software itself along with application programs, the operating system, and network software (if it is used over a network).
Data bridges the machine and human components
Procedures consist of instructions on how to log on to the DBMS, how to start and stop it, how to make backup copies, handle hardware and software problems etc.

14. Data Life Cycle Data acquisition Data use
data modeling and populating with ultimate goal of storing data
Data use
Combines data that has been previously stored and interprets output in a decision making context (Data Warehousing)
In Access, Tables deal with the first stage of the life cycle (data acquisition) and Queries, Forms and Reports deal with the second stage (data use) 17

15. Data acquisition Logical database design Physical database design
E/R diagrams, normalization, database models
Physical database design
Integrity constraints, indexes, denormalization
Populating the database
data entry, import, download
Update records
data dictionary, metadata
Data modeling and design are the responsibility of the IT group whereas populating the database is the responsibility of the functional manager(s) that use the data 18

16. Data Use Define view Retrieve data Manipulate data Present results
Query design, DDL (SQL or QBE)
Retrieve data
Query performance and optimization, concurrency controls
Manipulate data
Sort, aggregate, classify, analyze
Present results
Reports, forms
Query design and processing is the province of the IT professionals, whereas manipulation and presentation is the purview of the end-user
In Access, Queries deal with the first three and reports and forms deal with the last
Forms are primarily used for data entry and reports for printouts 20

17. Access Database Objects
Tables
Stores data as records
Queries
Answers questions about the database
Forms
Presents data using a customized layout
Reports
Formats the data (primarily for printouts)
Macros
Used to automate repetitive tasks
Modules
Pages
Tables contain the permanent data
Query datasheets are temporary
Modules require programming in Basic.
Note: Access automatically saves the active database periodically and when you close. So do not remove the diskette from the drive when the database is open.
The SAVE button saves the design of the table, query, form or report.
Although for Word you can undo last 100 changes, for Access you can only undo the last one.
Access saves changes in the current record as soon as you move to the next or when you close the table.

18. Users Administrators Data Administrator Database Administrator
Database designers
Conceptual and logical design (WHAT?)
Physical design (HOW?)
Application programmers
End users
naïve (e.g checkout assistant)
sophisticated
DA manages data and consults with senior managers to ensure that the database supports corporate objectives.
The DBA is more technically oriented and is in charge of security and integrity control and ensures satisfactory performance for the application and the users.
The importance of the corporate resources is reflected in the allocation of teams of staff to each role (in some organizations there is no distinction between the DA and the DBA)
The logical database designer is concerned with the data, the relations between the data and the constraints on the data (must know business rules) 9

19. Everyday Database Systems
Supermarket
Credit card
Travel Agent
Insurance
Library
University
1) Purchase goods and the barcode reader finds the price of each item from a products database and reduces the number of items on stock.
2) When you use your credit card to purchase goods, a card reader linked to a computer system checks the database to see if the price of goods you wish to buy along with the sum of purchases you have already made this month is within your credit limit. The program also checks that the card is not on the list of lost or stolen cards before authorizing the purchase. When your purchase is confirmed,the details of the purchase are added to the database.

20. Applications of DBMS Airline reservations systems Banking systems
Reservations (customer name, assigned seat)
Flights (airports, arrival and departures)
Tickets (prices, requirements, availability)
Banking systems
Customers (names, addresses, accounts, loans)
Corporate records
Accounts (payable, receivable)
Employees (names, addresses, salary, benefits)
Airline:
Queries: Which seats available and at what prices
Modifications: Book a flight, assign a seat, indicate a meal preference
Protect against data loss if system fails, Protect against two agents assigning the same seat
Banking:
Queries: Account balance
Modifications: Deposit to account
If money has been ejected from ATM machine the bank must record the debit even if the power fails immediately
Corporate:
Queries: Printing of weekly paychecks
Modifications: Employees fired or hired 16

21. Creating a Table in Access
Datasheet view
To add, delete or edit records
Design View
To define table the initially and specify its fields
In Word or Excel you can have several documents open at a time. But Access only allows you to open one database at a time.
Table names must start with a letter and cannot contain spaces.
Field names can contain (not at the start) spaces.
Given the choice between one wide field and several narrow ones, the latter is more flexible. (It is easier to concatenate fields than to separate one large field into several sub-fields.)
Leave extra room for growth in numeric data items.
Do not store calculated data on a record (use dates rather than numbers to represent time duration). .

22. Custom Tables Validation rules Input masks Default values
Lookup fields
Format
To set a validation rule linking two fields in a table use table properties
Input masks ease data entry by providing formatting
Lookup wizard can be used to look up values from a field in another table
Use >(<) in Format to convert all letters to upper (lower)case
Can state criteria for advanced filters
Tools->Analyze->Documenter builds a data dictionary for each object in the database

23. Advantages of Database Processing
Getting more information from the same amount of data
When all the data for various systems are stored in a single database, the information becomes available, as well as the process of retrieving the information can be quick and easy
Combine budget and resources to create important applications for the whole organization.
Information is quickly and easily accessible, since it is integrated

24. Advantages of Database Processing
Sharing of data
Several users can have access to the same piece of data (Concurrency control allows shared access)
Balancing conflicting requirements
A person or group, often called Database Administration/Administrator (DBA) can structure the database in such a way that it benefits the entire organization, not just a single group
Can write new applications for same data with DBA balancing users’ conflicting requirements

25. Advantages of Database Processing
Controlling redundancy
Not only saves space, but makes the updating process easier
Consistency
Consistency is a direct result of redundancy, so by reducing redundancy, there is much less potential for this sort of inconsistency with the database approach
Reducing redundancy improves consistency
e.g. in 1805, Austria, Britain, Russia &Sweden were at war with Napoleon. The Austrian and Russian commanders collaborated on a combined attack of the French Army. They agreed to meet on Oct 20th but the Austrians were using the Gregorian calendar whereas the Russians were still using the Julian calendar which was 10 days behind and so the Austrians got wiped out. (However, Napoleon was defeated at the Battle of Trafalgar by Nelson on Oct 21st and so did not invade Britain.)
A Mars probe was lost in Sep 1999 due to a mix-up by its flight controllers between imperial and metric units

26. Advantages of Database Processing
Integrity
An integrity constraint is a rule that must be followed by data in the database
Example: Not allowing a person’s age to be lower than zero
Security
The prevention of access to the database by unauthorized users
Recovery control restores the data to previous consistent state after hardware/software failure
According to European legislation, it is a criminal offense if data is not accurate or up-to-date

27. Advantages of Database Processing
Increasing productivity
A good DBMS comes with many features that allow users to gain access to data without having to do any programming at all
Data independence
A property that allows the structure of a database to be changed without the programs that access the database having to change
Information is quickly and easily accessible, since it is integrated
Reduced program maintenance for programmers due to data independence, improved data accessibility for end-users

28. Disadvantages of Database Processing
DBMS size
DBMSs are large programs that occupy a large amount of disk space as well as internal memory
DBMS complexity
The complexity and breadth of the functions provided by a DBMS make it a complex product to use
Mainframe multi-user projects are complex, with recurrent annual maintenance costs
Also costs of converting legacy systems (hardware, training etc.)
A file-based system is written for a particular application, so performs well, but DBMS is more general, so not as fast.

29. Disadvantages of Database Processing
Greater impact of a failure
A failure on the part of any one user that damages the database in some way may affect all the other users on the system
More difficult recovery
If the database is being updated by a large number of users, all updates must be redone since the time of its restoration
Greater vulnerability to multiple users as well as poor design.
Failure on the part of any user that damages the database will affect all users sharing that database
Multiple users mean that all updates will have to be restored

30. When can an organization justify a database?
Application needs are constantly changing
Rapid access is required for ad hoc queries
Need to reduce long lead times and high development costs for new systems
Data elements are shared by users
Need to communicate and relate data across functional and departmental boundaries
Need to improve quality of data resources and control access to them
Uncertainty as to important data elements and expected volume
Substantial dedicated programming assistance is not available
Need to improve quality and consistency of data resources 14

31. History of DBMS
IBM developed the Generalized Update Access Method (GUAM) in 1964 for North American Rockwell, the prime contractor for the APOLLO project
GUAM was made available for the general public under the name Data Language/I (DL/I) in 1966

32. History of DBMS
DL/I became the data management component for the Information Management System (IMS), which was the dominant DBMS for many years
In the mid-1960s, General Electric developed Integrated Data Store (I-D-S)
Enterprises nowadays maintain two distinct databases,
one containing operational or production (day to day) data
another containing decision support data (summary data that is extracted periodically from the operational database)

33. History of DBMS First generation Second generation Third generation
Hierarchical and network models
Second generation
Relational models
Third generation
Object oriented models

34. Data Models Record Based Object Based Hierarchical (60’s)
Network (70’s)
Relational (80’s)
Object Based
Entity-Relationship (70’s)
Semantic data models (80’s)
Object-oriented (90’s)
Relational systems specify what data is to be recovered
Network and hierarchical systems specify how the data is to be recovered
Even the most complicated hierarchical and network models can be represented using a relational model (2-dimensional tables)
Forms the basis for future object oriented databases

35. Record-Based Data Models
Hierarchical
Parent-child relationships with only one parent (N:1 relationships are not supported)
Network
Extends hierarchical model by allowing multiple parents
Associations are created via pointers
Relational
Hierarchical models evolved from tape systems
Suited for sequential processing
Generally not implemented on PCs
DML is more difficult than SQL or QBE
Relational DBMS is the dominant data processing software in use today 23

36. Hierarchical Model
Perceived by the user as a collection of hierarchies, or trees
More restrictive structure than a network model
GUAM, DL/I, and IMS are examples of DBMSs that conform to the hierarchical model
Represents data as composed of a hierarchy of data records
Tree structures (parent-child relationships, with only one parent record type allowed for any record type).

37. Network Model
Perceived by the user as a collection of record types and relationships between these record types
I-D-S is an example of a DBMS that conforms to the network data model
Represents data as records and relationships are represented by sets
(records appear as nodes and sets as edges in the graph)

38. Assignment 1 MS Access 2000 Pages AC 2.34 –2.36 #1-16
Database should have at least 4 entities