CS100: Introduction to Computer Science

Transcription

1 Statistics of the Secod Exam CS100: Itroductio to Computer Sciece Lecture 21: Database & Data miig 100 ad above: : : : : 3 Review: Course Objectives Review: Course Objectives Fudametal uderstadig of the field, Experiece with programmig, ad Fudametal uderstadig of the field, Experiece with programmig, ad Research topics ad applicatios Database & Data Miig Iformatio Retrieval & Questio Aswerig &Web Search Research topics ad applicatios Database & Data Miig Iformatio Retrieval & Questio Aswerig &Web Search Database Systems Relatioal Database Models Database A collectio of related records The coceptual view: table with rows ad colums Schema A structural descriptio of the type of facts held i a database E.g. (EmployeeID, Name, Address, Salary, JobNo) Relatioal model Domiat i commercial data processig systems Hierarchical model a tree structure, paret-child relatioships, 1:m mappig Network model More tha 1 paret per child, m : m mappig Your ow example? Database models : modelig database structure Object-orieted model Add database fuctioality to object programmig laguage. 1

2 Relatioal Database Model Relatio: A rectagular table Attribute: A colum i the table Tuple: A row i the table A relatio cotaiig employee iformatio A relatio cotaiig redudacy A employee database cosistig of three relatios Relatioal Operatios The SELECT operatio Select: Choose rows Project: Choose colums Joi: Assemble iformatio from two or more relatios 2

3 The PROJECT operatio The JOIN operatio Aother example of the JOIN operatio A applicatio of the JOIN operatio Structured Query Laguage (SQL) Operatios to maipulate tuples isert update delete select SQL s select EmplId, Dept from ASSIGNMENT, JOB where ASSIGNMENT.JobId = JOB.JobId ad ASSIGNMENT.TermData = * isert ito EMPLOYEE values ( 43212, Sue A. Burt, 33 Fair St., ) 3

4 SQL s (cotiued) delete from EMPLOYEE where Name = G. Jerry Smith update EMPLOYEE set Address = 1812 Napoleo Ave. where Name = Joe E. Baker Set Operators (SQL) UNION ALL Combies the results of two SELECT statemets ito oe result set. UNION Combies the results of two SELECT statemets ito oe result set, ad the elimiates ay duplicate rows from that result set. MINUS Takes the result set of oe SELECT statemet, ad removes those rows that are also retured by a secod SELECT statemet. INTERSECT Returs oly those rows that are retured by each of two SELECT statemets. Database Systems A relatioal database maagemet system A software package used to create a database (Oracle, Microsoft SQL sever, MYSQL) The coceptual layers of a database implemetatio Database applicatios Huma resource maagemet system Sales maagemet system Ivetory maagemet system Decisio support system Data Miig What is data miig? What is data miig Basic data miig tasks Data is growig at a pheomeal rate Users expect more sophisticated iformatio How? UNCOVER HIDDEN INFORMATION DATA MINING 4

5 Basic Data Miig Tasks -- Classificatio Maps data ito predefied groups or classes Credit card compay must determie whether to authorize credit card purchases. Four classes: 1) Authorize, 2) Ask for further idetificatio before authorizatio 3) do ot authorize, 4) do ot authorize but cotact police How to classify a purchase? Your ow example? Techiues: Regressio, Bayesia classificatio, Decisio trees (20-uestios game), Neural etwork Basic Data Miig Tasks--clusterig Groups similar data together ito clusters. (The clusters are ot predefied) A departmet store chai creates special catalogs targeted to various demographic groups based o attributes such as icome, locatio, etc. Basic Data Miig Tasks Associatio Rules Associatio Rules Idetify items are freuetly purchased together. A grocery store retailer is tryig to decide whether to put bread o sale. He fids that 60% of the time that bread is sold so are pretzels ad 70% of the time jelly is also sold by usig associatio rules. Decisios? Aoucemets: Homework 5: Due ext Moday (May 7 th ). Write a 2-page essay to discuss computer applicatios i your academic area. For example: Ecoomics, Biology, etc. Cover curret applicatios ad discuss potetial future applicatios This writte assigmet should be typed. Lab 6 this week: (optioal) Next lecture: Iformatio Retrieval, Questio Aswerig & Web search 5