Post on 31-Dec-2015
HAP 709: Healthcare Databases
Introduction to Database StructuresJanusz Wojtusiak, Ph.D.
Fall 2010
Based on slides by:Farrokh Alemi, Ph.D.
Francesco Loaiza, Ph.D. J.D.
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 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.
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, …
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 search through billions of information items in a fraction
of a second?
Flat Models
Student ID
NameMidterm
gradeFinal grade
Address Zip code ...
4561 Ali Safaie B A1311 Manor Park
22101 ...
7878Mike Smith
C B1619 Ozkan Street
44115 ...
8954Mike
Smith Jr.A C
2121 Euclid 563
22101 ...
Flat DataAdvantages• 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
Hierarchical models
Data models in which the relationship between higher and
lower items are inherited.
Advantages of Hierarchical Models
Advantages
• Operations on parents save time and affect all children.
Disadvantages
• Many relationships are not hierarchical
Relational Databases
In a relational database, tables do not need to be of the same size
In a relational data base, one stores a record with related fields
as data.
ExampleTable for "Students grades"
Student IDKey column
Name Mid-term Final
4561 Ali Ghadiri B A
7878 Mike Smith C B
8954 Mike Smith Jr. A C
Table for "Students' contact information"
Student ID Address Zip
8954 2121 Euclid 563 22101
4561 1311 Manor Park 22101
7878 1619 Ozkan Street 44115
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.
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.
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
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
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
Data-less Information Systems
Distributed Databases without data until need arises, less
problems with privacy of patients
Sometimes called federated databases.
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.
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.