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.

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.data 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?

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

Flat Models Student ID Name Midterm grade Final grade AddressZip code Ali SafaieBA 1311 Manor Park Mike Smith CB 1619 Ozkan Street Mike Smith Jr. AC 2121 Euclid

Flat Data How do we keep two addresses for the same student? What if there are five addresses?

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

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

Example of Hierarchal Model Person Employee Patient Contractor Admin Clinical ICU Clinic

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.

Example Table for "Students grades" Student ID Key column NameMid-termFinal 4561Ali GhadiriBA 7878Mike SmithCB 8954Mike Smith Jr.AC Table for "Students' contact information" Student IDAddressZip Euclid Manor Park Ozkan Street44115

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.

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 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.

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