Download Introductions. DB=tables,records, fields. 3-tier

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 email
– 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and ASP out-of-date!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, email, 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)
Players table
ER diagram
player_id
Question databank table
Player name
question_id
Score
Question
lastplayed date
Answer (answer pattern)
Value
0
history table
question_id
Category
player_id
whenplayed
0
correct
Data flow diagram (process
diagram) for quiz show
Player
History DB
Play
game
Player scores
Questions DB
Edit questions
Editor
Create quiz tables (php
only)
Include/Required
file: opendbq
Input Questions
(handles form input)
Choose category
Show
scores
Ask question
Storyboard
Check answer
Clear tables
ER diagram for on-line
store
Product catalog
Product id
Product name
Picture
Cost
Customer list
Customer ID
first name
last name
Billing information
E-mail
Password
0
0
Ordered items
Order ID
Product
Quantity
Order list
Order ID
Customer ID
Date
Status
Total
Data flow (process)
diagram for on-line store.
Customer
Catalog
Browse/
Order
Customer list
Current orders
Billing
Ordered items
Shipping
Billing system
(timed event)
Shipping clerk
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)
Input products
Include/require:
opendbo
Delete current
customer cookie
Order product
makeorder
Submit order
Shopping cart
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
– http://faculty.purchase.edu/jeanine.meyer/html5
/html5logoscale.html Shows slider (range)
– http://faculty.purchase.edu/jeanine.meyer/html5
/bouncingballinputsimg.html Checks for
numbers in the indicated range
– http://faculty.purchase.edu/jeanine.meyer/html5
/addmessage.html radio buttons. Opera
browser supplies color palette
Server-side / Middleware
extra credit
opportunity
• 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)
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 email
– 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 email 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 online 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