Lec9Handout

Transcript Lec9Handout

Information Visualization Course
Web Design
Prof. Anselm Spoerri
[email protected]
© Anselm Spoerri
Lecture 9 – Overview
Dynamic Web
Programming Concepts
PHP
– Introduction | Basic Operations & Coding
MySQL
– Introduction | Simple Queries
MySQL & PHP
– Set Up PHP Testing Server in Dreamweaver
– login.php
– Connect to whereru Database
– Run Query & Process Results
Source: "Learning PHP, MySQL, and JavaScript" by Robin Nixon.
© Anselm Spoerri
Web Pages Created So Far
Static HTML Pages
– Same each time
Want Interactive or Dynamic Web Pages
– Depending on browser, time of day or user behavior or …
different appearance
– Processing user inputs data via HTML forms
– Need some sort of Web programming (JavaScript, PHP)
© Anselm Spoerri
Basic Client/Server Request/Response Sequence
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Dynamic Client/Server Request/Response Sequence
$query
$result
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Dynamic Web
1. JavaScript
– Client-side scripting access to elements of HTML document
– Perform data handling and web server requests in background
2. PHP
– Server-side scripting
– Open source, simplicity and built-in links to MySQL database
3. MySQL
– Open-source Relational Databases that supports structured
queries and is free to use and install on web servers
4. Apache Server
– Open source server software that serves up HTML, media files etc
PHP handles main work on web server, MySQL manages data, and JavaScript looks after web page
presentation. JavaScript can also talk with your PHP code on the web server whenever it needs to
update something (either on the server or on the web page).
© Anselm Spoerri
Key Programming Concepts
Key Programming Concepts
data types
numbers, text, boolean (true, false)
variable = container of data
array = collection of data organized in a sequence
statement
= combination of variables, operators and data
 group of statements
 function
= collection of statements to perform specific task
perform test: true or false
if (test) then
for loop: where do we start? when are done? how to continue?
© Anselm Spoerri
Programming Concepts – Overview
Data Types: such as numbers,
text, boolean (true, false)
‒
Integer | Boolean | Character | String | Floating-Point
‒
Array: [5, 4, 7]
(use FOR loop to examine each array item)
Variable: is way to symbolically
‒
to refer to data content
scores = [5, 4, 7];
Operators: can be used to perform built-in operations
‒
5 +5;
(where + is addition operator)
Statement: combination
‒
of variables, operators and data
total = 12 * monthly_average;
© Anselm Spoerri
Programming Concepts – Overview
Function:
collection of statements to perform specific task
function add_scores (score1, score2)
{
return (score1 + score2);
}
total = add_scores (3, 4);
Conditional Programming
used so that operations are
performed only if certain condition is met:
‒ IF test (only do something if certain condition is true)
‒ FOR loop (keep doing something only if certain condition is true)
‒ WHILE loop (keep doing something until certain condition not
true anymore)
Debugging code
is essential part of programming ...
chasing typos, missing parentheses :)
© Anselm Spoerri
PHP – Overview
http://en.wikipedia.org/wiki/PHP
Open-source
http://www.php.net : documentation
Server-side scripting
– Insert content of one file (or the output of a system call) into
another file dynamically
– Create images and other files for you, either on the fly or in advance
to serve up later.
– PHP program responsible for passing back clean file suitable for
display in web browser.
Simplicity & Flexibility
Built-in links to MySQL database
.php
file extension
<?php
echo "Hello World. Today is ".date("l").".";
?>
© Anselm Spoerri
PHP – Overview
(cont.)
<?php
// This is a comment or
?>
/* multiline comments */
$count = 10;
Must Place $ in front of all Variables
Common Error = Forget Semicolon
$username = "Fred Smith"; // quotation marks for string
echo $username; // echo makes variable visible in Browser
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PHP – Code Construction
XHTML tags included inside of PHP code
(thus have DOCTYPE declaration and basic XHTML structure)
Some programmers open tag at start of document and close it at the end,
outputting any HTML directly from PHP commands.
<?php
echo "Hello World. Today is ".date("l").".";
?>
Others choose to insert only smallest possible fragments of PHP within
these tags wherever dynamic scripting is required, leaving the rest of the
document in standard HTML.
Hello World. Today is <?php echo date("l"); ?>.
Latter style may produce faster code, while the former has less complexity
having to drop in and out of PHP many times in a single document.
© Anselm Spoerri
PHP - Variable Naming Rules
Starts with
$
Variable Naming Rules
When creating PHP variables, you must follow these four rules:
‒
Must start with a letter of alphabet or _ (underscore)
‒
Can contain only the characters: a-z, A-Z, 0-9, and _
‒
May not contain spaces.
‒
Variable names are case-sensitive.
(e.g., $user_name).
The variable $High_Score is not the same as the variable $high_score.
In PHP, & symbol tells parser to pass reference to variable's value,
not the value itself.
Be careful when passing values by reference. If you need to keep
the original values, make copies of your variables and then pass
the copies by reference.
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PHP - Strings
PHP supports two types of strings: "hello" or 'hello'
– Literal string (preserve exact contents), use apostrophe:
$info = 'Preface variables with a $ like this: $variable';
– Include value of variable (evaluate string): use quotation
marks
$count = 44;
echo "There have been $count presidents of the US";
Escape Character : \
– $text = 'My friend\'s car is a Chevy';
– $text = "My mother always said \"Eat your greens\".";
– Important to use
when
HTML code and variables used inside echo statement
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PHP – Array Operations
$team = array('Bill', 'Joe', 'Mike', 'Chris'); // apostrophes
echo $team[3]; // Displays the name Chris
 array indexes start at
zero
$twoDim = array(array('a', '', 'c'), array('', 'b', ''),);
echo $twoDim[1][1];
count($a);
// number of array items
Array union: $a + $b
Associative Array
– $a['firstname'] = "John";
© Anselm Spoerri
PHP - Operators
Operators
++$j
or
--$j
// Increment or Decrement
"FirstName" . " " . "LastName"
Boolean AND: && AND
$firstname && $lastname
Equality Operator is ==
// String concatenation
OR: || OR
$firstname || $lastname
Not Equal is !=
Identity Operator is === (prevents type conversion)
Operators precedence rules  use parentheses to control what
gets computed first and in which order
© Anselm Spoerri
PHP – Constants, Global and Function
Define Constant
define("ROOT_LOCATION", "/usr/local/www/");
–
–
Can not be prefaced with $ sign and need to use define function
Use UPPERCASE
global $username;
Define Function
function function_name ([parameter [, ...]]) {
// Statements }
function squared ($count) { return $count * $count;}
Scope of Variable
– Local variables are accessible just from part of code where defined:
Defined inside of function, only accessible inside of function.
Defined outside of function, only accessible outside of function.
– Global variables are accessible from all parts of your code.
Forgetting Scope of Variable is Common Error.
© Anselm Spoerri
PHP – IF test
if (test) {do1;} else {do2;}
<?php
$a = "1000";
$b = "+1000";
if ($a == $b) {echo "equal";} else { echo "not equal";}
if ($a === $b) {echo "identical";} else { echo "not identical";}
?>
test ? doifTRUE : doifFALSE;
if (test1) {do1;} elseif (test2) {do2;} else {do3;}
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PHP – FOR Loop AND FOREACH Loop
for loop
for (init variable ; test variable ; increment variable) {
do something;
}
for ($count = 1 ; $count <= 12 ; ++$count) {
echo "$count times 12 is " . $count * 12 . " ";
}
foreach loop used for arrays
$paper = array("Copier", "Inkjet", "Laser", "Photo");
$j = 0;
foreach ($paper as $item) {
echo "$j: $item ";
++$j;
}
© Anselm Spoerri
PHP – Include Code from Other Files
include_once "filename";
– Tell PHP to fetch a particular file and load all its contents
– To avoid error of trying to define same constant or function multiple
times
require_once "filename";
– To make sure that file is found
© Anselm Spoerri
PHP – Questions
What tag is used to cause PHP to start interpreting program code?
What are the two types of comment tags?
Which character must be placed at the end of every PHP statement?
Which symbol is used to preface all PHP variables?
What can a variable store?
What is the difference between $variable = 1 and $variable == 1?
Why do you suppose that an underscore is allowed in variable names ($current_user)
whereas hyphens are not ($current-user) ?
Are variable names case-sensitive?
Can you use spaces in variable names?
How do you convert one variable type to another (say, a string to a number)?
Are the operators && and and interchangeable?
Can you redefine a constant?
How do you escape a quotation mark?
How can you make a variable accessible to all parts of a PHP program?
What is the result of combining a string with a number?
© Anselm Spoerri
SQL – Querying Relational Database
SQL = Structured Query Language
http://en.wikipedia.org/wiki/SQL
Database computer language designed for
Managing & Accessing Data in Relational
Database
Queries
– Ask question about data
– Receive answer back by returning subset of table data.
– Use JOIN, SELECT, WHERE
– Need semicolon ; at the end of query
– SQL commands and keywords are case-insensitive
© Anselm Spoerri
MySQL – Overview
Open-source
http://www.mysql.com/
Fast & Powerful Yet Easy-to-use Database
– One or more tables that contain your data
Database
– The overall container for a collection of MySQL data.
Table
– A subcontainer within a database that stores the actual data.
Row
– A single record within a table, which may contain several fields.
Column
– The name of a field within a row.
SQL commands and keywords are case-insensitive
© Anselm Spoerri
MySQL – Overview
(cont.)
Field
– The name of each field or column within a table.
Type
– The type of data being stored in the field.
Null
– Whether a field is allowed to contain a value of NULL.
Key
– MySQL supports keys or indexes, which are quick ways to look
up and search for data. The Key heading shows what type of
key (if any) has been applied.
Default
– The default value that will be assigned to the field if no value is
specified when a new row is created.
© Anselm Spoerri
Set Up PHP Testing Server
If not already done to access DW via SoftwareAnywhere:
login to http://account.comminfo.rutgers.edu to provision credentials
Site > New Site
Select “Site”
Site > Site Name = “PHP Testing Server”
Site > Local Site Folder = “PHPfiles” in “My Documents”
Select “Servers" Category in Site Dialog
Click on + (Add new server)
Specify Server Name
Select “SFTP" in pull-down “Connect using” menu
SFTP Host = “cactuar.scilsnet.rutgers.edu”
Root Directory =
“/www/whereru.scils.rutgers.edu/htdocs/iti320semesteryear/yourteam”
where for example semesteryear = su13 or fa13
Login = “yourNetIDusername”
Password = “yourNetIDpassword”
Web URL =“http://whereru.rutgers.edu/iti320semesteryear/yourteam”
Test
Advanced Tab: Select “PHP MySQL” in pull-down Server Model menu
Save
Make sure “Remote” and “Testing” checkboxes are selected
© Anselm Spoerri
Testing PHP Page
Preview in Browser
Update Copy on Testing Server?
Select “Yes”
Put Dependent Files ?
Select “No“
Permissions
Folder / Files Permission Automatically set to 770 … you don’t have do anything
Folder for Each Team Member
Need to update:
Root Directory =
“…/iti320semesteryear/yourteam/username”
where for example semesteryear = su13 or fa13
for example: “…/iti320fa13/yourteam/username”
Web URL
=“http://whereru.rutgers.edu/iti320semesteryear/yourteam/username”
for example:
“http://whereru.rutgers.edu/iti320fa13/yourteam/username”
© Anselm Spoerri
Site Definition for PHP Testing Server
Local Folder = YOUR files and Upload Your Files to Your Server Folder
Local Folder = contains YOUR PHP files
Root Directory =
“<code not included>/iti320fa13/yourteam/username”
Web URL = http://whereru.rutgers.edu/iti320fa13/yourteam/username
Local Folder = Contains Folder for YOUR files and Upload Your Files to Your
Server Folder
Local Folder = contains a folder that contains YOUR PHP files and this folder
needs to have same name as YOUR folder on the server.
Root Directory =
“<code not included>/iti320fa13/yourteam/”
Web URL =“http://whereru.rutgers.edu/iti320fa13/yourteam/
 Number of Local Folder Hierarchy Levels needs to match
Number of Server Folder Hierarchy Levels
If the local folder of your Site Definition contains just your PHP files, then your
Site Definition needs to include the name of YOUR folder on the server so
that your PHP files get automatically uploaded to YOUR folder on the server.
If the local folder of your Site Definition contains a folder that contains your PHP
files, then your Site Definition does not need to include the name of YOUR
folder on the server so that your PHP files get automatically uploaded to
YOUR folder on the server.
© Anselm Spoerri
MySQL & PHP – Process Steps
The process of using MySQL with PHP:
1. Connect to MySQL.
2. Select the database to use.
3. Build a query string.
4. Perform the query.
5. Retrieve the results and output it to a web page.
6. Repeat Steps 3 to 5 until all desired data retrieved.
7. Disconnect from MySQL (usually done automatically)
© Anselm Spoerri
MySQL & PHP – login.php for your database
Create login.php file
<?php
// login.php
make sure to place in personal folder
make sure to place in personal folder
$db_hostname = 'localhost';
$db_database = 'whereru';
$db_username = 'yourMySQLusername';
$db_password = 'yourMySQLpassword';
?>
Upload to Server, View Source in Browser
Now that you have login.php file saved, you can include it in any
PHP files that will need to access the database by using the
require_once statement.
© Anselm Spoerri
MySQL & PHP – Connect to Database – Step 1
<?php // connectDatabase.php
require_once 'login.php';
$db_server = mysql_connect($db_hostname, $db_username,
$db_password);
if (!$db_server)
die("Unable to connect to MySQL: " .
mysql_error());
mysql_select_db($db_database) or die("Unable to select
database: " . mysql_error());
?>
© Anselm Spoerri
MySQL & PHP – Query Database – Step 2
Add to connectDatabase.php
$db_table = 'whereru_gigapan';
// description in Sakai
Resources
$query = "SELECT
$result =
* FROM
$db_table";
mysql_query($query);
if (!$result) die ("Database access failed: " . mysql_error());
© Anselm Spoerri
MySQL & PHP – Display Query Result – Step 3
Add to connectDatabase.php
$rows = mysql_num_rows($result);
for ($j = 0 ; $j < $rows ; ++$j){
echo 'ID: ' .
mysql_result($result,$j,'id') . ' ';
echo 'Title: ' . mysql_result($result,$j,'title') . ' ';
echo 'Campus: ' . mysql_result($result,$j,'campus') . ' ';
}
This code is inefficient and slow, because $rows * 3 calls are made to the function
mysql_result in order to retrieve all the data.
© Anselm Spoerri
MySQL & PHP – Display Query Result (improved) – Step 4
$id = 0; // assign index needed to access field in $row array … see data info in Sakai
$title = 2;
$campus = 3;
for ($j = 0 ; $j < $rows ; ++$j) {
$row =
mysql_fetch_row($result);
// returns array
echo 'ID: ' . $row[$id] . ' ';
echo 'Title: ' . $row[$title] . ' ';
echo 'Campus: ' . $row[$campus] . ' ' . ' ';
}
© Anselm Spoerri
MySQL & PHP – Refined Query
$db_table = 'whereru_gigapan';
$query = "SELECT * FROM $db_table WHERE campus='Newark'";
$result = mysql_query($query);
if (!$result) die ("Database access failed: " . mysql_error());
$rows = mysql_num_rows($result);
$id = 0;
// assign index needed to access field in $row array
$title = 2;
$campus = 3;
for ($j = 0 ; $j < $rows ; ++$j) {
$row = mysql_fetch_row($result); // returns array
echo 'ID: ' . $row[$id] . ' ';
echo 'Title: ' . $row[$title] . ' ';
echo 'Campus: ' . $row[$campus] . ' ' . ' ';
}
© Anselm Spoerri