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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. What is database?. Is an Excel table with students’ grades a database? Is your notebook a database?
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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
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?
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 can go through billions of information items in a fraction of a second?
Types of Data Structures • Flat data • Hierarchical data • Relational data • Object-oriented data
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
In a relational data base, one stores a record with related fields as data. Relational Databases In a relational database, tables do not need to be of the same size
Example Table for "Students grades" Table for "Students' contact information"
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.
Hierarchical models Data models in which the relationship between higher and lower items are inherited.
Example of Hierarchal Model • File items on your desk top
Advantages of Hierarchical Models Advantages • Operations on parents save time and affect all children. Disadvantages • Many relationships are not hierarchical
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
Example of Distributed Database World Wide Web
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
Data-less Information Systems Distributed Databases without data until need arises, less problems with privacy of patients
Components of a Data-less System • Decoder • Communicator • Analysis
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.
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.
Take Home Lesson Structure makes it possible to process and analyze large amount of data