1. Data, Information, and Databases BDIS 6.1
BSAD 141
Dave Novak

2. Topics Covered Information types: transactional –vs- analytical
Five characteristics of information quality
Database versus a DBMS
RDBMS: advantages and terminology
Multi-user issues

3. The Need for High-Quality Information
Data are everywhere
Which data are important?
Which data should the organization store?
Which data need to be further manipulated?
Which data are required to make different types of decisions?
How does the organization convert various data into information that is needed?

4. The Need for High-Quality Information
Recall difference between data and information from Lecture #1

5. The Need for High-Quality Information
The need to obtain and analyze the many different levels, formats, and granularities of organizational information to make decisions
Granularity refers to the extent of detail within the information (fine and detailed or “coarse” and abstract information)

6. The Need for High-Quality Information
CRITICAL TO REMEMBER!
Decisions are only as good as the quality of the data and information that are used to make the decisions…
Crap in  Crap out
Using technology to help you make a decision using poor quality data doesn’t help

7. Example of Low Quality Data
Data Quality Problems
Example of Low Quality Data
Issue 1: Without a first name it would be impossible to correlate this customer with customers in other databases (Sales, Marketing, Billing, Customer Service) to gain a compete customer view (CRM)
Issue 2: Without a complete street address there is no possible way to communicate with this customer via mail or deliveries. An order might be sitting in a warehouse waiting for the complete address before shipping. The company has spent time and money processing an order that might never be completed
Issue 3: If this is the same customer, the company will waste money sending out two sets of promotions and advertisements to the same customers. It might also send two identical orders and have to incur the expense of one order being returned
Issue 4: This is a good example of where cleaning data is difficult because this may or may not be an error. There are many times when a phone and a fax have the same number. Since the phone number is also in the address field, chances are that the number is inaccurate
Issue 5: The business would have no way of communicating with this customer via
Issue 6: The company could determine the area code based on the customer’s address. This takes time, which costs the company money. This is a good reason to ensure that information is entered correctly the first time. All incorrect information needs to be fixed, which costs time and money

8. Characteristics of High Quality Information
1) Accurate
2) Complete
3) Consistent
4) Unique
5) Timely
Characteristics of High Quality Information

9. 1) Accurate
Are the data (is the information) correct, precise, and exact?
For example:
Are the data factual?
Are values error-free?
Have data been verified?
Correct spelling
Precise numbers
Accuracy Are all the values correct? For example, is the name spelled correctly? Is the dollar amount recorded properly?

10. 2) Complete
Are the data whole (complete) and do they have all the necessary parts?
For example
Are there missing values or pieces of data?
Full street address
Area code along with phone number
Empty fields
Full Names
Completeness Are any of the values missing? For example, is the address complete including street, city, state, and zip code?

11. 3) Consistent
Are the data are in agreement with themselves and with known facts?
For example
Does summary information agree with detailed information? Can you reconcile the data?
Do mathematical manipulations yield correct results?
Are data manipulations performed consistently for the entire data set?
Consistency Is aggregate or summary information in agreement with detailed information?
For example, do all total fields equal the true total of the individual fields?

12. 4) Unique
Are the data unique (one of a kind) or are there redundant, repetitious or unnecessary data stored in the same database?
For example:
Are there duplicate records for the same “event”?
Are there different versions of “the same” file or event (which is the latest or most accurate?)
Uniqueness Is each transaction, entity, and event represented only once in the information?
For example, are there any duplicate customers?

13. 5) Timely Are the data current with respect to decision-making needs?
Timeliness depends on the situation
Real-time information – Immediate, up-to-date information
Real-time system – Provides real-time information in response to requests
“Real-time” is a relative description that depends on the use or need
Timeliness Is the information current with respect to the business requirements? For example, is information updated weekly, daily, or hourly?

14. How can data be of “poor” quality?
Customers intentionally enter inaccurate information to protect their privacy or because they are irritated
Different data entry standards and formats
Operators enter abbreviated or erroneous information by accident or to save time
Third party and external information contains inconsistencies, inaccuracies, and errors
Addressing the above sources of information inaccuracies will significantly improve the quality of organizational information
Determine a few additional sources of low quality information
A customer service representative could accidentally transpose a number in an address or misspell a last name

15. What is a Database?
Database – a collection of information organized in a way that provides efficient retrieval
There are electronic and physical databases (paper/print)
A database can be a very simple collection of data such as alphabetically arranging names in an address book

16. What is a Database Management System (DBMS)?
Database management systems (DBMS) – A set of computer programs / software that allow users to store, modify, query, and retrieve data in a systematic and controlled manner

17. Database Management System (DBMS)
A database (the physical collection of data) is typically not portable across different DBMS
Like application software, different DBMS are generally designed to work with specific system software and specific database schema
A database is typically something inside the DBMS, although in the case of a MS Excel workbook the database is a standalone object

18. Database Management System (DBMS)
A very popular and common DBMS is the relational DBMS (RDBMS)
A standard program and user interface is the Structure Query Language (SQL)
A programming language used to create, modify, and retrieve information from a database
Different databases use different (proprietary) variations to standard SQL

19. Database Management System (DBMS)
According to the following source (which I did not verify with the Gartner report) the top five commercial RDBMS vendors in 2011 were:
Oracle (≈ 50% market share)
IBM (≈ 20% market share)
Microsoft (≈ 17% market share)
SAP
Teradata

20. Database Management System (DBMS)
Oracle: Oracle Database and MySQL
IBM: DB2 and Informix
Microsoft: SQL Server
SAP: Sybase Enterprise and Sybase IQ
Teradata

21. Single File Data Management
MS Excel is a database, but it is not a DBMS!
Each worksheet is a single large two-dimensional matrix
A database is simply an organized collection of data that can be accessed
A DBMS is software that is used to manage the database and provides a set of tools used to manipulate and query data

22. Relational Database Management System (RDBMS)
Data are organized as a set of formal tables
Data can be accessed and combined in different ways without reorganizing the data within the tables
Data can be manipulated in different ways and combined with data in other tables without altering the original data in the table
RDBMS can be easily extended / scaled – new data and new categories of data can be added without changing existing data

23. RDBMS Terminology
Data model – A picture of logical data structures that detail the relationships among data elements
Metadata – Formal description of data structures (like tables and fields) and any constraints of the table or values within the table
Data about the containers of data

24. RDBMS Terminology
Data dictionary – Compiles all of the metadata about the elements in the data model

25. Entity Sets (Tables)
Relational table or entity set – Each table consists of columns (fields/attributes) and rows (records/entities)
The table has a name that describes the group of related entities within the table
For example, a table labeled “Student” would contain a group of student entities

26. Entity / Record / Row
A person, place, thing, transaction, or event about which data are being collected and stored
The individual rows in a table contain entities
Each row is also referred to as a record
Example?

27. Attributes / Field / Column
The data elements that describe the characteristics of a specific entity
The columns in each table contain the attributes
Example?

28. What is a Relationship?
1) When designing a relational DB, data need to be separated into tables that contain related data elements
For example we would not store data related to customer (name, address, phone, etc.) and data related to the customer’s particular order (orderID, date, shipping method, etc.) in the same table

29. What is a Relationship?
All information specific to a customer would go into a “Customer” table
All information specific to the specific orders would go into an “Order” table
We would then create a relationship between the tables to match a particular customer with a particular order

30. What is a Relationship?
A relationship in an RDB is an association between the entities within the different tables
There are THREE (3) types of relationships:
One-to-One (1:1)
One-to-Many (1:M)
Many-to-Many (M:M)

31. Creating Relationships Through Keys
KEYS are used to create relationships between the entities in different tables in the RDB
Primary key
Foreign key

32. Creating Relationships Through Keys
For our purposes:
Every table in a RDB MUST have a primary key
The foreign key is not required in every table and will only appear on the “many” side of the relationship

33. Advantages of RDBMs
RDBMS advantages from a business perspective include
1) Flexibility
2) Scalability and performance
3) Improved information integrity (quality)
Reduced information redundancy
4) Information security
A good way to explain databases is to compare them to spreadsheets
What are the limitations when using a spreadsheet?
Limited number of rows and columns (Excel - 65,536 rows by 256 columns) Once you use more than 65,536 rows you have outgrown your spreadsheet
Only one user can access the spreadsheet
Users can view all information in the spreadsheet
Users can change all information in the spreadsheet
All of the disadvantages associated with a spreadsheet are fixed when using a database

34. 1) Flexibility Handle changes quickly and easily
Provide users with different views of the data
Arranging data items in different ways depending on the user need
Showing a particular user only some of the available fields while not showing them other fields

35. 1) Flexibility: Schema
Different database schema can be “owned” by or associated with different users
The schema is a user personalized set of tables, views, and indexes

36. 2) Scalability and Performance
A DBMS must expand to meet increased demand, while maintaining acceptable performance levels
Scalability – Refers to how well a system can adapt to increased demands
Performance – Measures how quickly a system performs a certain process or transaction
What happens to a business if its suddenly experienced a 60 percent growth in sales and its IT systems fail with all of the increased activity?

37. 3) Information Integrity
Information integrity – a measure of information quality
Know that data have not been entered incorrectly or altered in an unauthorized manner
Integrity constraint – rules that help ensure the quality of information
We will discuss entity integrity and referential integrity (there is also domain integrity)
Can you define two relational integrity constraints for an ordering system?
Users cannot create an order for a nonexistent customer
An order cannot be shipped without an address
Can you define two business-critical integrity constraints for an ordering system?
Product returns are not accepted for fresh product 15 days after purchase
A discount maximum of 20 percent

38. 3) Information Integrity: Controlling Redundancy
Redundant data are ok if they serve a specific purpose such as being used as backup directly linked to the source
Backup systems promote fault tolerance,
Unintentional redundancy is not good
Wasted storage
Difficult to modify
Possible inconsistencies

39. 4) Information Security
Information is an organizational asset and must be protected
RDBMS offer several security features
Access level – Determines the level of access each individual user has
Who can access the DBMS
Access control – Determines the types of things each group can do
Types of access, such as power to create, modify, delete, and/or read
Which types of SQL statements can be executed
Why you would want to define access level security?
Access levels will typically mimic the hierarchical structure of the organization and protect organizational information from being viewed and manipulated by individuals who should not have access to the sensitive or confidential information
Low level employees typically have the lowest levels of access
High level employees typically have access to all types of database information
For example: You would not want analysts viewing all salary information for the entire company - in general:
Analysts can usually only view their own salary
Managers have higher access and can view the salaries of all their team members, but cannot view other managers’ salaries
Directors can view all of their managers’ and analysts’ salaries, but not other directors’ salaries
The CFO and CEO can view every employee’s salary

40. Multiuser Issues DBMS serve many different users with different needs
Many users may require concurrent access to the same data
Must preserve integrity of data and the performance of the system

41. Multiuser Issues
Problem: if multiple users (say tens or even hundreds of users) access the same data concurrently, how does the DBMS allow one user to change data without being overwritten by another user? This is typically referred to as the Lost-update problem

42. Multiuser Issues
Concurrent transactions are addressed through the use of transactions and locks
Transactions – single indivisible action that affects some data
Once a transaction is committed, it is permanent and changes are visible to all users
If transaction is not committed, changes are “rolled back” or reversed

43. Multiuser Issues
Locks – literally “locks” the data so that changes cannot be made on the data while another transaction is in process

44. Enterprise DBMS

45. Learning Outcomes Five characteristics of quality information
Define database, DBMS, RDBMS, and supporting components and terminology
Advantages of RDBMS
What is SQL?
Describe the lost-update problem and how it is addressed