1. HAP 709: Healthcare Databases
Introduction to Database Structures
By Farrokh Alemi, Ph.D.
Francesco Loaiza, Ph.D. J.D.
Updated by Janusz Wojtusiak, Ph.D.
Fall 2008

2. What is database? Is an Excel table with students’ grades a database?
Is your notebook a database?
Is a phonebook a database?
Is the GMU schedule of classes a database?
Is a medical record of a patient a database?
Is a list of nurses working in a hospital a database?

3. What is database?
Database is a collection of data with defined structure and purpose.
Wikipedia: A Database is a structured collection of data which is managed to meet the needs of a community of users.
Wordnet: Database is an organized body of related information.

4. What is computer database?
Computer database is a database stored in a computer.
It is usually managed by special software called Database Management System (DBMS).
There are many DBMS systems available
Access, Oracle, MUMPS, dBASE, portgress, sql server, mysql, db2, …

5. Objectives of this lecture
Learn about flat, hierarchical, relational, and object-oriented databases
Learn about information-less databases
If checking an information item takes a fraction of a second, why is it that we can go through billions of information items in a fraction of a second?

6. Types of Data Structures
Flat data
Hierarchical data
Relational data
Object-oriented data

7. Flat Models Student ID Name Midterm grade Final grade Address Zip code
...
4561
Ali Safaie B A
1311 Manor Park
22101
7878
Mike Smith C
1619 Ozkan Street
44115
8954
Mike Smith Jr.
2121 Euclid 563

8. Flat Data
Advantages
Most software include free access to flat data files.  For a small number of cases, flat databases do a reasonably fast job.
Most analytical software use flat data.
Disadvantages
Flat databases waste computer storage by requiring it to keep information on items that logically cannot be available.
Flat databases are not conducive to complicated search queries

9. In a relational database, tables do not need to be of the same size
Relational Databases
In a relational data base, one stores a record with related fields as data.
In a relational database, tables do not need to be of the same size

10. Table for "Students grades"
Example
Table for "Students grades" 
Student ID Key column
Name
Mid-term
Final
4561
Ali Ghadiri B A
7878
Mike Smith C
8954
Mike Smith Jr.
Table for "Students' contact information"
Student ID Key column
Address
Zip
8954
2121 Euclid 563
22101
4561
1311 Manor Park
7878
1619 Ozkan Street
44115

11. Advantages of Relational Databases
Data can be examined from many different perspectives. 
No need to enter missing information for variables that are not logically possible.
Easy to modify because adding new concepts involves adding new Tables, not altering old ones.

12. Hierarchical models
Data models in which the relationship between higher and lower items are inherited.

13. Example of Hierarchal Model
File items on your desk top

14. Advantages of Hierarchical Models
Operations on parents save time and affect all children.
Disadvantages
Many relationships are not hierarchical

15. Object-oriented data models
Data are organized in the form of “objects” that represent real world entities. Each objects have its properties, that can be regular values or other objects.

16. Advantages of Object-oriented models
High efficiency
Use of the actual “real life” entities as objects
Integration with object-oriented programming languages (C++, Java, C# …)
Disadvantages
Lack of one good standard

17. Distributed data models
Data are kept in different settings and on different computers. Distributed databases need not only addresses for where the data are but also need an audit trail

18. Example of Distributed Database
World Wide Web

19. Advantages of Distributed Databases
Security of these databases are difficult to maintain.
Many agreements must be made ahead of time.
Data loss is limited to nodes affected.
Decentralized databases are more flexible and allow different units to update and maintain their own data. 
Variation in quality of data

20. Data-less Information Systems
Distributed Databases without data until need arises, less problems with privacy of patients

21. Components of a Data-less System
Decoder  
Communicator  
Analysis

22. Advantages of the Data-less Information Systems
The system is substantially less expensive than centralized registries as it requires no new equipment and little personnel.  
The use of the system does not require vague and time-independent patients’ consents.  
The system does not require duplication of data in different databases.

23. Inductive Databases
Researchers investigate databases that can answer questions about things which are not in that databases. They use artificial intelligence to give “plausible” answers.

24. Take Home Lesson
Structure makes it possible to process and analyze large amount of data