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What is a 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?. What is database?. Database
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1. HAP 709: Healthcare Databases Introduction to Database Structures
Janusz Wojtusiak, Ph.D.
Fall 2010
Based on slides by:
Farrokh Alemi, Ph.D.
Francesco Loaiza, Ph.D. J.D.
2. What is a 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
6. Types of Data Structures Flat data
Hierarchical data
Relational data
Object-oriented data
7. Flat Models
8. Flat Data
How do we keep two addresses for the same student?
What if there are five addresses?
9. 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
It is almost impossible to design flat models for things with varying numbers of properties
Flat databases are not conducive to complicated search queries
10. Hierarchical models Data models in which the relationship between higher and lower items are inherited.
11. Example of Hierarchal Model
12. Advantages of Hierarchical Models Advantages
Operations on parents save time and affect all children.
Disadvantages
Many relationships are not hierarchical
13. Relational Databases In a relational database, tables do not need to be of the same size
14. Example
15. 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.
16. 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.
17. Advantages of Object-oriented models Advantages
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
18. 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
HAP 720
19. Advantages and Disadvantages 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
Sometimes called federated databases.
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 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 explicitly 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