CSCI 6442 Database Management II INTRODUCTION Copyright 2016 David C. Roberts, all rights reserved

Agenda How the course works ◦Homework ◦Project ◦Exams ◦Grades Prerequisite ◦CSCI 6441: Mandatory prerequisite ◦Take the prereq or get permission to take the course Goals of the course ◦Advanced topics ◦Topics that are often not understood ◦Realistic experience Workload ◦Fairly heavy workload from the beginning ◦Workload gets heavier when project starts Relational Principles ◦Why relational, why it matters 2

Homework Weekly assignments Assignments are challenging and make an important point, no busywork Submit assignments by to No attachments Assignments due at start of class Late assignments not accepted 3

Project One project will involve the entire class Work will be performed in functional teams Every student must produce programs, will be graded on personally produced results Details of project not yet determined 4

Project We have a choice about the project ◦We can build a multi-enterprise Web-accessed application with general usefulness as a WordPress plugin. ◦You can take it with you and use it as you wish in the future ◦It’s a good thing to show for grad school or job interviews ◦We can include both transaction and analytical processing in the project ◦We can do a big data experiment with a lot of data ◦New York City has made large data collections available ◦We can get accounts on Amazon Web Services ◦This would be a one-time project, no takeaways Previous project built by a CSCI 6442 class: QuestionPeach.com 5

Exams Midterm and final Midterm will be closed book, in class Midterm date will not change Plan your schedule now: ◦Be here for the midterm, no makeup exams ◦Be here for the final, no makeup exams Midterm will test your ability to work with concepts discussed in lecture and covered by homework 6

Grading A: Good quality graduate work, only minor issues with correctness B: Acceptable graduate work, one or more major issues C: Not acceptable graduate work, several serious issues F: Does not show basic understanding 7

Prerequisites CSCI 6441 is a mandatory prerequisite Take it before this course If you think you know the material, you need to explain it and get permission First assignment is intended to clear this up 8

Goals Misunderstood topics ◦Normalization ◦Database design ◦Performance ◦SQL Advanced topics ◦Time in databases ◦Translucency ◦Performance Realistic experience ◦Realistic team size ◦Accountability ◦Emerging requirements Current Developments ◦Big data ◦NOSQL ◦Cloud Computing 9

Workload This course is for advanced students who want to be technical leaders of a database project If want to “slide by,” you are in the wrong course But if you do want to be the database guru on a project at work, then stay in this course! 10

Relational Principles Earlier database systems: hierarchies, networks as data models ◦Relationships represented as physical connections ◦Structure of relationships imbedded in applications ◦When relationships changed, applications had to change Relational: independent table as data model ◦Relationships represented by equal values ◦Structure of relationships invisible to applications ◦Relationships can change structure without application change 11

Relational Database Relational Database: a set of relations 12

Relation Relation: a set of ordered pairs Ordered pair: a pair of values, such that interchanging the two values changes the meaning ◦That is, = iff a = b and b = a Specifying a relation by enumeration: R = {,, } ◦This is a relation consisting of three ordered pairs. 13

Relation and File Ordered pairs can model more than two values through nesting: ◦ ==, c> ◦ ==, c, d> ◦And so on This extends the ordered pair so that it can model a tuple of any length Now a relation starts to look like our notion of a file, with each tuple corresponding to our notion of a record 14

The Definition Relation is a set of ordered pairs (modeling a set of tuples), so: 1. exchanging order of values within a tuple changes the meaning of the tuple 2. exchanging the order of tuples within a relation does not change the meaning of the tuple 3. duplicate tuples are not allowed 15

Data Modeling Now we build a database as a collection of independent relations, each describing instances of a single entity type For example: ◦Employee (employee#, job, salary, department) ◦Department (department#, departmentname, location) (this is called schema notation) 16

Data Language We need a way to insert data into the database, retrieve data from the database, and changes values that are stored in the database We define a data language that can be used from any programming language to do that The data language (SQL) has a lot of power and can save a lot of programming work if you understand it You’ll have a brief chance to learn more about SQL in this course 17

Normalization Database courses talk about normalization Students usually don’t learn more than memorizing definitions We will talk about Roberts’s Rules, plain English rules that give you a highly normalized database Then we will talk about the normalization rules and what they mean in English You will have the chance to really understand how to do this 18

Time Time in databases is a complex issue There’s the time something happened and the time it’s entered into the database And there’s also the effective time, which may differ from those two times And there’s the need to capture a history of previous values and roll back to it We’ll examine all of these cases of time 19

Translucency Typically the GRANT statement is used to give access to a database A DBA enters the statement, and a user has access But that’s not good enough if there may be thousands of people on the Web using a database We’ll study translucency, a way to provide access control without GRANT statement 20

Responsibility Professional standards, like the work environment, will be followed: ◦Arrive at class on time ◦Submit homework on time ◦Limit answers to 50 words 21

Class Web Site A class Web site has been established Everything about the class is on it ◦Assignments ◦Lecture slides ◦Papers Please read it When changes are made to the site a note will be sent to the class list It’s at 22

list A class list has been established If you got the sent today, then you’re on it If not, please go to the site, follow instructions, and enroll yourself You can follow instructions on the Web site to enroll a different address 23