Creating Databases for Web applications Introductions & overview Administration Moodle HW: Sign on, register for course, introduce yourself on Moodle. Post source on php.

Introductions Jeanine Meyer, Mathematics/Computer Science –Ph.D. in Computer Science –IBM Research, IBM EduQuest (corporate grants) Pace University Consulting/K-12 Faculty development –books: Multimedia in the Classroom, Programming Games using Visual Basic, Creating Databases for Web Applications with PHP and ASP, Beginning Scripting through Game Creation, The Essential Guide to HTML5, HTML5 and JavaScript projects, Elementary Number Theory with Programming –Hobbies/Interests: piano, flute, politics, community volunteer, origami, grandchildren, programming! You

NOTE The HTML5 and JavaScript Projects book (on reserve in Library) has chapters –HTML, php for sending –HTML, php, MySQL example

General objectives Learn how to learn –Practice looking up and using sources Learn how to build large[r] applications –Make proposals, make and use diagrams –Work in teams Make presentations Practice concise writing –Blog entries, abstracts (1-pagers)

Moodle Instructional support tool IT IS A REQUIREMENT that you check this regularly. –You will be required to make postings to specific Discussion Forums. Hopefully, you will make additional postings. –You are required to read postings.

References There will be assignment(s) to find and describe on-line sources Many online and off-line reference –Note: Creating Web Databases with PHP and ASP out-of-date! Coding examples in book for old php. though much is relevant: general background on middleware, HTML, SQL. Design of examples. –HTML5 and JavaScript Projects book better!

Course structure Each day will include lecture, demonstration, discussion, exercises Required postings, homework Team presentations: explanation and enhancements of sample projects Midterm plus pop quizzes one original project (can be team) –initial presentation, with diagrams –Final presentation, including demonstration, showing of working code Extra credit: talks on suggested topics (for example, alternatives to php such as ASP.net, Ruby on Rails; alternatives to SQL; Big Data; etc.)

Course content Course content: practical and (some) theoretical tools for creating Web applications involving databases. (Systems design) Describe (logical) function using diagrams –Entity relationship –Data Flow diagrams –Storyboard (Systems build) Requires middleware=server-side tools. We will use Open Source software (PHP and MySQL)

What is a data base? A data base is organized information. A data base management system (DBMS) is a product that supports implementation & use of databases. HOWEVER, generally, the term database is reserved for something using a standard relational DBMS tool –DBMS is the product/tool: MySQL, Access, (Oracle, DBII, etc.) –The specific database, for example, the [toy] database examples for this course, are implemented using a particular DBMS

Examples of things not a relational database Flat file –For example, will show php code used for the state capital quiz. This is an example of parallel structures: two arrays, one for the names of the states and one for the names of the capitals. XML file Linked lists Hash table Key-value pairs

Big Data partially a marketing term / buzz word Attributes are –volume -- big –velocity – changes a lot… –variability – greatly variable in formats plus attribute that the organization using it may not control the data Example: analyzing uses of a term (say, "fiscal cliff") in twitter posts over a set time frame OR last N postings. Requires mixture of techniques.

A relational Database …consists of tables –Tables hold records (= rows) Records hold fields = attributes (= columns) A relational database supports fields in a record that point to/link/refer to records in the same or other tables. Database(s) most probably exist on campus –student table: major, gpa, address. –course table: section, instructor, time, location –enrollments: section & student, semester

All together now Database –Tables Records –Fields Relationships: fields that refer to records in the same or other tables.

Database terminology Primary key: field that uniquely defines a record. Often generated automatically by DBMS foreign key: field in record in one table that ‘is’/points to a record in another table Or to a record in the same table. The field with the foreign key would not be the primary key field. –orderlist = table of orders. Each order includes as one of the fields a customer id. This customer made the order.

Work up example Information is: courses, sections, enrollments, teachers, schedule, more? What are the tables? What are records in each table? NOTE: it takes time to design a database.

Structured Query Language Unlike much else in computing, databases follow standards. Everything said so far applies to MySQL, Access, Oracle, PostgreSQL etc. SQL is … [a] structured query language. –SELECT question, answer, points FROM questions WHERE category = chosencategory –INSERT INTO customers VALUES (fname, lname, billing, , pass) Syntax (format & punctuation) is tricky!

MySQL Open source dbms we will use with php. (some actions) done using phpmyadmin –May do initial definition of tables –May use for debugging did my php script put something in my database? We (our php code) create(s) SQL to access / modify the database

Systems Design …refers to functional specification of system (what it should do, not especially how it looks or how it is done) Use diagrams to specify databases, processes, scripts/Web pages. –tools (computer aided systems engineering=CASE tools) & methodologies exist. We will be less formal. Create diagrams using PowerPoint or any drawing tool.

Diagrams Are important! Will use [at least] 3 types in this course –Entity relationship Show data and relationships –Data flow Show agents, programs, data stores –Story board Connections between programs (scripts)

Question databank table question_id Question Answer (answer pattern) Value Category Players table player_id Player name Score lastplayed date history table question_id player_id whenplayed correct 0 0 ER diagram

Player Editor Play game Edit questions Questions DB Player scores Data flow diagram (process diagram) for quiz show History DB

Create quiz tables (php only) Input Questions (handles form input) Choose category Ask question Check answer Clear tables Include/Required file: opendbq Show scores Storyboard

Product catalog Product id Product name Picture Cost Customer list Customer ID first name last name Billing information Password Order list Order ID Customer ID Date Status Total Ordered items Order ID Product Quantity 0 ER diagram for on-line store 0

Customer Billing system (timed event) Browse/ Order Billing Catalog Customer list Current orders Ordered items Shipping clerk Shipping Data flow (process) diagram for on-line store. Note that this is the information/data flow, not the flow of goods. The shipping operation produces a physical product: the collection of ordered items, packed and set off for delivery.

Storyboard of partial implementation: ordering Create tables (php only) Include/require: opendbo Input products Order product makeorder Shopping cart Submit order Delete current customer cookie Include/require: displaycartfunction

Web terminology: standard Web files are stored on the server computer. The browser (IE, Firefox, Opera, etc.) is on the client computer. Hypertext Markup Language (HTML) files are requested by the browser from the server and interpreted by the browser. This could include display of image files, playing of video or audio, etc. Stateless system: server does not ‘remember’ anything between requests.

but, stateless-ness wasn’t good enough … to support real, practical applications involving –files and databases –state information—information valid across multiple pages Need for so-called middleware / server-side Alternatives were/are Common Gateway Interface (cgi) programming and Java applets.

Three-tier implementation model Code to be run on the client (by browser) –HTML and JavaScript Code to be run on the server –php Code (queries) executed by the DBMS –SQL queries constructed by php code

Three tier logic model Presentation Business logic Information

Cloud computing extends / replaces 3 tier model. NOTE: much use of data NOT in an organization's possession or control. –Note: company can use ("rent") storage & processing in "the cloud" and still control/own the data. OR –Use data from other organizations Example: access Twitter for latest tweets.

HTML5 new features include form validation: specifying what is expected in input elements of forms and promising that browser will perform those checks Show – /html5logoscale.html Shows slider (range) /html5logoscale.html – /bouncingballinputsimg.html Checks for numbers in the indicated rangehttp://faculty.purchase.edu/jeanine.meyer/html5 /bouncingballinputsimg.html – /addmessage.html radio buttons. Opera browser supplies color palettehttp://faculty.purchase.edu/jeanine.meyer/html5 /addmessage.html

Server-side / Middleware Files (aka scripts) ‘in’ PHP (or ASP, cold fusion, ruby on rails, perl, etc.) are requested by browser. However, the server processes the PHP instructions in the files to –produce an HTML file for interpretation by the browser and –access & modify data (files, databases) on the server. NOTE: database(s) are on the server! –store & access so-called cookies on the client computer. Cookie is a special, small file. HTML5 term: localStorage (Flash term: sharedstorage) extra credit opportunity

Development / testing for class Create / register to have MySql database We/you will create html/JavaScript files PLUS php files Upload all files to your site (account) Some php files (aka scripts) will access (read & write) MySql Some html and php files will populate (put data into) html tables

Contrast This is not like general practice of testing on your computer and later uploading complete tested application!

PHP Personal Home Page  PHP: Hypertext Preprocessor Language plus a set of built-in procedures and properties –language includes support for user-defined objects. Open Source

Warnings SQL is a very powerful language. –It may take time to produce 1 SQL statement The equivalent of many lines of code in another programming language. Writing php code, including code generating SQL statements, can involve complex syntax –For example, single quotes within double quotes –References to variables within quoted strings.

General format of SELECT SELECT [modifier such as DISTINCT] field1, field2, expression [COUNT(field)] FROM tablea, tableb, … WHERE condition(s) GROUP BY fieldx ORDER BY fieldy HAVING condition LIMIT n, m

$sel="SELECT question_id, question, ans, value from questions "; $sel= $sel. " WHERE category= '". $pickedcategory. "'"; $result=mysql_db_query($DBname, $sel, $link); $NoR=mysql_num_rows($result); Single quote within double quotes

Reprise When we write php, we write –plain HTML –php that uses functions that use operating system on server read/write files send –php that produces HTML –php that sends SQL to MySQL and gets results back that php uses to produce HTML

Confirmation on information so far What is a database? A database is made up of …. Describe 3 tier model –operationally (implementation) in terms of [what] code –functionally (logic) in terms of what function

continued… What does browser do? What does it interpret? What is done on/by the server? What is done by the DBMS (MySQL)?

Homework Go to students.purchase.edu and sign up for webspace AND database –Don't sign up for webspace if you already have it and don't sign up for database if you already have it. –You will get an with information. Your account will be on socialsoftware.purchase.edu Visit Moodle course site. –Introduce yourself on Introductions, etc. forum. –Find, briefly review and post your assessment of an on- line source for PHP on Resources YOU find forum. –Must be unique. If someone has done "yours", find another site. –NOTE: will repeat this for other topics