1. DATABASES AND DATA WAREHOUSES A Gold Mine of Information
CHAPTER 4
DATABASES AND DATA WAREHOUSES
A Gold Mine of Information

2. Today, Organizations Need...
4-2
Introduction
Today, Organizations Need...
Information to compete effectively
Information just to stay alive in the information age
Information organized in such a way that you can easily and quickly get to it
Information-processing tools that help you work with information

3. YOUR FOCUS IN THIS CHAPTER
4-3
Introduction
YOUR FOCUS IN THIS CHAPTER
The Difference Between Logical and Physical Views of Information
Databases and Database Management Systems
How You Can Develop Database Applications
Data Warehouses and Data Mining Tools

4. THREE THINGS ORGANIZATIONS DO WITH INFORMATION
4-4
Information Revisited
THREE THINGS ORGANIZATIONS DO WITH INFORMATION
1.Process information in the form of transactions
2.Use information to make a decision
3.Manage information while it’s used

5. PROCESSING INFORMATION IN THE FORM OF TRANSACTIONS
4-5
Information Revisited
PROCESSING INFORMATION IN THE FORM OF TRANSACTIONS
Such as payroll processing, order processing, and handling your registration requests for classes.
This is called ONLINE TRANSACTION PROCESSING (OLTP) - the gathering of input information, processing that information, and updating existing information to reflect the gathered and processed information.
Operational databases support OLTP.

6. USING INFORMATION TO MAKE A DECISION
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Information Revisited
USING INFORMATION TO MAKE A DECISION
For answering such questions as, “How many senior-level marketing majors have not taken statistics?”
This is called ONLINE ANALYTICAL PROCESSING (OLAP) - the manipulation of information to support decision making.
Data warehouses support OLAP.

7. MANAGING INFORMATION WHILE IT’S USED
4-7
Information Revisited
MANAGING INFORMATION WHILE IT’S USED
Determining who can view or use information
Specifying how to back up information
Identifying what storage technologies to use
Most importantly, managing information includes organizing it so that people can logically use it without having to know anything about its physical structure. The difference between logical and physical is key.

8. 4-8
Information Revisited
In managing information, physical deals with the structure of information as it resides on various storage media.
Logical deals with how knowledge workers view their information needs, and includes such terms as:
CHARACTER - our smallest unit of information.
FIELD - group of related characters.
RECORD - group of related fields.
FILE - group of related records.
DATABASE - group of logically associated files.
DATA WAREHOUSE - information from many databases.

9. 4-9
Databases
DATABASE
a collection of information that you organize and access according to the logical structure of that information.
A database is actually composed of two parts:
1. the information itself
the files that are logically associated
2. the logical structure of the information
called the data dictionary

10. A Database Is a Collection of Information
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Databases
A Database Is a Collection of Information
Most databases contain two or more files with related information.
The Inventory database (Figure 4.4, page 125) contains two files - Part and Facility.
These two files are logically related because parts are stored in facilities and because you would use both of these files to manage your inventory.

11. A Database Contains a Logical Structure
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Databases
A Database Contains a Logical Structure
You organize and access a database by its logical structure, not its physical position.
DATA DICTIONARY - contains the logical structure of information in a database.
The data dictionary contains the logical properties that describe information in a database.
See Figure 4.5 (page 126) for the data dictionary of the Percentage Markup field in the Inventory database.

12. A Database Has Logical Ties Among the Information
4-12
Databases
A Database Has Logical Ties Among the Information
A PRIMARY KEY is a field in a database file that uniquely describes each record.
A FOREIGN KEY is a primary key of one file that also appears in another file. So, foreign keys specify how files are logically related.
For example, the Part and Facility files are logically related. So, in Figure 4.4 you can see that Facility Number (the primary key for the Facility file) exists in the Part file (where it’s a foreign key).

13. A Database Contains Built-in Integrity Constraints
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Databases
A Database Contains Built-in Integrity Constraints
An INTEGRITY CONSTRAINT is a rule that helps assure the quality of the information in a database.
A registration database at your school includes integrity constraints concerning prerequisites for certain classes.
Our Inventory database includes an integrity constraint that says a part in the Part file cannot be assigned to a facility that does not exist in the Facility file.

14. DATABASE MANAGEMENT SYSTEM (DBMS)
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Database Management Systems
DATABASE MANAGEMENT SYSTEM (DBMS)
the software you use to specify the logical organization for a database and access it.
A DBMS contains 5 software components:
1. DBMS engine
2. Data definition subsystem
3. Data manipulation subsystem
4. Application generation subsystem
5. Data administration subsystem

15. 4-15
DBMSs
DBMS ENGINE
accepts logical requests from the various other DBMS subsystems, converts them to their physical equivalent, and actually accesses the database and data dictionary as they exist on a storage device.
Recall that:
PHYSICAL VIEW deals with how information is physically arranged, stored, and accessed on some type of secondary storage device.
LOGICAL VIEW focuses on how you need to arrange and access information to meet your particular business needs.

16. DATA DEFINITION SUBSYSTEM
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DBMSs
DATA DEFINITION SUBSYSTEM
helps you create and maintain the data dictionary and define the structure of the files in a database.
You use this subsystem to define the information logical structure when you first create a database.
Once you’ve created a database, you use this subsystem to define new fields, delete fields, or change field properties.
Figure 4.5 (page 126) contains this subsystem screen for the Part file.

17. DATA MANIPULATION SUBSYSTEM
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DBMSs
DATA MANIPULATION SUBSYSTEM
helps you add, change, and delete information in a database and mine it for valuable information.
This subsystem is most often the primary interface between you as a user and the information contained in a database.
Tools in this subsystem include views, report generators, query-by-example tools, and structured query language.

18. DATA MANIPULATION TOOLS
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DBMSs
DATA MANIPULATION TOOLS
VIEW - allows you to see the content of a database file, make whatever changes you want, perform simple sorting, and query to find the location of specific information. See Figure 4.7 page 129.
REPORT GENERATOR - helps you quickly define formats of reports and what information you want to see in a report. See Figures 4.8 and 4.9 page 130.

19. DATA MANIPULATION TOOLS
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DBMSs
DATA MANIPULATION TOOLS
QUERY-BY-EXAMPLE (QBE) TOOL - helps you graphically design the answer to a question. Figure 4.10 (page 130) shows the QBE for displaying the names and phone numbers of facility managers in charge of parts that cost more than $10.
STRUCTURED QUERY LANGUAGE (SQL) - a standardized fourth-generation language found in most database environments. SQL is the same as QBE, except that you perform a query by creating a statement instead of pointing, clicking, dragging.

20. APPLICATION GENERATION SUBSYSTEM
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DBMSs
APPLICATION GENERATION SUBSYSTEM
contains facilities to help you develop transaction-intensive applications. This subsystem includes:
Tools for creating data entry screens (See Figure 4.12 page 131 for an example)
Programming languages specific to a particular DBMS
Interfaces to commonly used programming languages that are independent of any DBMS.

21. DATA ADMINISTRATION SUBSYSTEM
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DBMSs
DATA ADMINISTRATION SUBSYSTEM
helps you manage the overall database environment by providing facilities for:
Backup and recovery
Security management
Query optimization
Reorganization
Concurrency control
Change management

22. THE RELATIONAL DATABASE MODEL
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Database Models
THE RELATIONAL DATABASE MODEL
a database model that uses a series of two-dimensional tables or files to store information.
This is the most popular model.
Each table is called a RELATION.
A relation contains information about a particular ENTITY CLASS (a concept - people, places, or things - about which you wish to store information and that you can identify with a unique key).

23. The entity classes are Customer, Video, Video Rental, and Distributor.
4-23
Database Models
Figure 4.14 (page 136) shows a relational database for a video rental store.
The entity classes are Customer, Video, Video Rental, and Distributor.
Notice how these tables are related to each other through the use of foreign keys.
In the Video Rental relation, you’ll find a primary key that uses more than one one field to create a unique description. This is called a COMPOSITE PRIMARY KEY.
A primary key that uses only one field is called an ATOMIC PRIMARY KEY.

24. THE OBJECT-ORIENTED (O-O) DATABASE MODEL
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Database Models
THE OBJECT-ORIENTED (O-O) DATABASE MODEL
a database model that brings together, stores, and allows you to work with both information and procedures that act on the information.
An OBJECT-ORIENTED DATABASE MANAGEMENT SYSTEM (O-O DBMS) is the DBMS software that allows you to develop and work with an O-O database.

25. See Appendix C for more on objects.
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Database Models
This model takes advantage of the concept of an OBJECT - a software module containing information that describes an entity class along with a list of procedures that can act on the information describing the entity class.
Figure 4.15 (page 138) shows the same video rental store using the O-O database model.
Notice that the objects (entity classes) - which include Customer, Video Rental, Video, and Distributor - contain both information and procedures for working with that information.
See Appendix C for more on objects.

26. DEVELOPING YOUR OWN DATABASE
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Developing Databases
DEVELOPING YOUR OWN DATABASE
Being able to develop your own database is a part of knowledge worker computing.
Building a database for your personal needs includes the following 4 steps:
1. Defining entity classes and primary keys
2. Defining relationships among entity classes
3. Defining information (fields) for each relation
4. Using a data definition language to create the database
Follow along as we build the database to support the report in Figure 4.16 on page 140.

27. #1 - DEFINING ENTITY CLASSES AND PRIMARY KEYS
4-27
Developing Databases
#1 - DEFINING ENTITY CLASSES AND PRIMARY KEYS
From the report in Figure 4.16, you can identify the entity classes as Employee, Department, and Job.
Now, for each entity class, you must define a primary key that provides a unique description. These include:
Employee entity class - Emp ID (e.g., 2345 for Smith)
Department entity class - Dept (e.g., 15)
Job entity class - Job (e.g., 14 for Acct)

28. #2 - DEFINING RELATIONSHIPS AMONG ENTITY CLASSES
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Developing Databases
#2 - DEFINING RELATIONSHIPS AMONG ENTITY CLASSES
For this step, use an ENTITY-RELATIONSHIP (E-R) DIAGRAM, a graphical method of representing entity classes and their relationships.
See Figure 4.17 (page 140) for the initial E-R diagram of our database and a listing of E-R diagram symbols.

29. An Employee must be assigned to a Department.
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Developing Databases
EMPLOYEE
M:1
DEPARTMENT
An Employee must be assigned to a Department.
An Employee cannot be assigned to more than one Department.
A Department may have many Employees assigned to it.
A Department is not required to have any Employees assigned to it.

30. Normalization includes the following 3 steps:
4-30
Developing Databases
After building the initial E-R diagram, you must follow the process of normalization.
NORMALIZATION is a process of assuring that a relational database structure can be implemented as a series of two-dimensional tables.
Normalization includes the following 3 steps:
1.Eliminate repeating groups or M:M relationships
2.Assure that each field in a relation depends only on the primary key of that relation
3.Remove all derived fields from the relations.

31. There is an M:M between Employee and Job.
4-31
Developing Databases
The first rule of normalization states that no M:M relationships can exist.
There is an M:M between Employee and Job.
You eliminate this by creating an INTERSECTION RELATION - a relation you create to eliminate a repeating group.
An intersection relation will have a composite primary key that consists of the primary key fields from the two intersecting relations.
In Figure 4.18 (page 142), we created an intersection relation called Employee-Job to eliminate the M:M relationship.

32. #3 - DEFINING INFORMATION (FIELDS) FOR EACH RELATION
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Developing Databases
#3 - DEFINING INFORMATION (FIELDS) FOR EACH RELATION
In this step, you follow rules #2 and #3 of normalization.
Your goal here is two-fold:
1.Make sure that the information in each relation is indeed in the correct relation
2.Make sure that the information cannot be derived from other information.

33. To determine if information is in the correct relation, ask:
4-33
Developing Databases
To determine if information is in the correct relation, ask:
“Does this piece of information depend only on the primary key for this relation?”
If the answer is yes, the information is in the correct relation.
In the Employee relation (Figure 4.20 page 144), we currently store Dept Sup. Does Dept Sup depend on Emp ID?
The answer is no - Dept Sup depends on Dept, so it should be in the Department relation.

34. For example, # Emp is a field in the Department relation.
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Developing Databases
Derived information - information that can be mathematically determined from other information - should not be stored in your database.
For example, # Emp is a field in the Department relation.
However, we can simply count the number of occurrences of each Dept in the Employee relation and determine the number of employees.
So, we remove # Emp from the database.

35. #4 - USING A DATA DEFINITION LANGUAGE TO CREATE THE DATABASE
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Developing Databases
#4 - USING A DATA DEFINITION LANGUAGE TO CREATE THE DATABASE
The final step is to actually create the relations you identified in steps 1-3.
You do this with a data definition language.
This step includes:
Developing a data dictionary
Defining the various relations
Defining primary keys and relationships

36. 4-36
Data Warehouses
DATA WAREHOUSE
a logical collection of information - gathered from many different operational databases - that supports business analysis activities and decision-making tasks. Data warehouses...
are a logical extension of databases
support OLAP
are among the newest and hottest buzz words and concepts in the IT field.

37. DATA WAREHOUSE FEATURES
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Data Warehouses
DATA WAREHOUSE FEATURES
Data warehouses combine information from different databases
Making them a true repository of all an organization’s information
Data warehouses are multi-dimensional
As opposed to 2 dimensions in the relational model
Often called hypercubes (See Figure 4.23 page 148)
Data warehouses support decision making
While databases support OLTP, data warehouses support OLAP

38. the software tools you use to query information in a data warehouse.
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Data Warehouses
DATA MINING TOOLS
the software tools you use to query information in a data warehouse.
QUERY-AND-REPORTING TOOLS - QBE tools, SQL, and report generators.
INTELLIGENT AGENTS - various artificial intelligence tools that form the basis for “information discovery” in OLAP.
MULTIDIMENSIONAL ANALYSIS (MDA) TOOLS - slice-and-dice techniques that allow you to view multidimensional information from different perspectives.

39. IMPORTANT CONSIDERATIONS IN USING A DATA WAREHOUSE
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Data Warehouses
IMPORTANT CONSIDERATIONS IN USING A DATA WAREHOUSE
Do you need a data warehouse?
Do you already have a data warehouse?
Who will the users be?
How up-to-date must the information be?
What data mining tools do you need?

40. MANAGING THE INFORMATION RESOURCE
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Managing Information
MANAGING THE INFORMATION RESOURCE
How will changes in technology affect organizing and managing information?
What types of database models and databases are most appropriate?
Who should oversee the organization’s information?

41. OVERSEEING YOUR ORGANIZATION’S INFORMATION
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Managing Information
OVERSEEING YOUR ORGANIZATION’S INFORMATION
CHIEF INFORMATION OFFICER (CIO) is the IT manager who directs all IT systems and personnel while communicating directly with the highest levels of the organization.
DATA ADMINISTRATION plans for, oversees the development of, and monitors the information resource.
DATABASE ADMINISTRATION is responsible for the more technical and operational aspects of managing information in databases.

42. MANAGING THE INFORMATION RESOURCE
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Managing Information
MANAGING THE INFORMATION RESOURCE
Is information ownership a consideration?
What are the ethics involved in organizing and managing information?
How should databases and database applications be developed and maintained?

43. TO SUMMARIZE How we view information:
4-43
TO SUMMARIZE
How we view information:
The physical view of information deals with how information is physically arranged, stored, and accessed on some type of secondary storage device.
The logical view of information focuses on how you need to arrange and access information to meet your particular business needs.
A database is a collection of information that you organize and access according to the logical structure of that information.
The data dictionary contains the logical structure of information in a database.

44. 4-44
TO SUMMARIZE
A database management system is the software you use to specify the logical organization for a database and access it.
Popular database models include the relational model and the object-oriented model.
The four steps of developing a personal database application include:
1. Define entity classes and primary keys
2. Define relationships among entity classes
3. Define information (fields) for each relation
4. Use a data definition language to create the database

45. 4-45
TO SUMMARIZE
Data warehouses are a logical collection of information - gathered from many different operational databases - that supports business analysis activities and decision-making tasks.
Data mining tools - the software tools you use to query information in a data warehouse - include query-and-reporting tools, intelligent agents, and multidimensional analysis (MDA) tools.