1. HCSI 709: Healthcare Databases
Introduction to Database Structures
By Farrokh Alemi, Ph.D.
Francesco Loaiza, Ph.D. J.D.
Voice of Vikas Arya

2. Objectives Learn about flat, hierarchical and relational 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?

3. Types of Data Structures
Flat data
Hierarchical data
Relational data

4. 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

5. 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.
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

6. 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

7. 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

8. 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.

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

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

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

12. 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

13. Example of Distributed Database
World Wide Web

14. 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

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

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

17. 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.

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