Internet Engineering Course

1
Internet Engineering Course

• Web Application Development

2
Introduction

• Company needs to provide various web services
• Hosting intranet applications
• Company web site
• Various internet applications
• Therefore there is a need to develop applications
• We should select web application model to use
• Discuss on different types of applications

3
Content

• Application development models
• SSI
• CGI with Perl
• LAMP/WAMP
• J2EE
• .Net
• Typical web applications in an organization
• CMS/DMS
• Groupware (Collaboration software)
• WIKI
• Workflow

4
SSI

• Server Side Includes
• This is very simple model, not really an
  application development model suitable for middle
  to large size applications
• Web server processes such instructions and
  generate dynamic content
• Directives that are placed in HTML pages, and
  evaluated on the server while the pages are being
  served.
• Let you add dynamically generated content to an
  existing HTML page, without having to serve the
  entire page via a CGI program, or other dynamic
  technology.

5
SSI

• SSI directives have the following syntax
• lt!--element attributevalue attributevalue ...
  --gt
• It is formatted like an HTML comment
• so if you don't have SSI correctly enabled, the
  browser will ignore it

6
SSI examples

• Commonly used to obtain and display environment
  variables from the OS
• lt!--echo var"DATE_LOCAL" --gt
• Modification date of the file
• This document last modified
• lt!--flastmod file"index.html" --gt
• Including the results of a CGI program
• lt!--include virtual"/cgi-bin/counter.pl" --gt
• Including a standard footer
• lt!--include virtual"/footer.html" --gt

7
SSI examples (cont.)

• Executing commands
• ltpregt lt!--exec cmd"ls" --gt lt/pregt
• Conditional expressions
• lt!--if expr"Mac InternetExplorer" --gt
  
• Apologetic text goes here
• lt!--else --gt Cool JavaScript code goes here
• lt!--endif --gt

8
SSI conclusion

• Minimize code duplications
• SSI for site management
• Creates dynamic content
• Can be a security problem

9
CGI

• Common Gateway Interface
• Invented in 1993 by NCSA for HTTPd web server
• Client requests program to be run on server-side
• Web server passes parameters to program through
  UNIX shell environment variables
• Program spawned as separate process via fork
• Program's output gt Results
• Server passes back results (usually in form of
  HTML)
• Good for interfacing external applications with
  information servers
• it is language independent
• CGI programs are most often written in PERL,
  C/C, VB, Java, or UNIX shell scripts.

10
CGI
Request service
Run CGI program print result
HEADERS BODY
11
CGI with Perl

• Write a standard Perl Program
• Program's output (to stdout) is sent back as HTTP
  Response
• You must write out everything
• Headers
• Blank Space
• Body

12
CGI with Perl

• Some CGI programs are in machine code, but Perl
  programs are usually kept in source form, so Perl
  must be run on them
• A source file can be made to be executable by
  adding a line at their beginning that specifies
  that a language processing program be run on them
  first
• For Perl programs, if the perl system is stored
  in /usr/local/bin/perl, as is often is in UNIX
  systems, this is
• !/usr/local/bin/perl
• The file extension .cgi is sometimes used for
  Perl CGI programs
• An HTML document specifies a CGI program with the
  hypertext reference attribute, href, of an
  anchor tag, ltagt, as in
• lta href ./cgi-bin/reply.cgigt" Click here to
  run the CGI program, reply.pl lt/agt

13
Perl

• Practical Extension and Reporting Language.
• Originally developed as a utility language for
  UNIX.
• Particularly well suited to manipulate patterns,
  especially text.
• Popular because it is free, available for most
  operating systems, and relatively easy to learn
• Exceedingly powerful, but noisy, and prone to
  errors.

14
Perl a simple example

• Hello World in Perl
• ! /usr/bin/perl
• print "Content-type text/html\n\n"
• print "lthtmlgtltbodygtlth1gtHello World!"
• print "lt/h1gtlt/bodygtlt/htmlgt\n"
• Simple concept -- the program executes, and the
  output is sent to the browser that called it.

15
Perl a simple counter

• ! /usr/bin/perl
• open (INPUT,count.txt)
• _at_inline ltINPUTgt
• count inline0 1
• close INPUT
• open (OUT,gtcount.txt)
• print OUT count\n
• close OUT
• print "Content-type text/html\n\n"
• print "lthtmlgtltbodygt
• print lth1gtLets Count! "lt/h1gt"
• print This page accessed count timesltpgt
• print lt/bodygtlt/htmlgt\n"

16
Perl Basic syntax

• Perl statements end in a semi-colon
• Comments start with a hash symbol and run to the
  end of the line
• Whitespace is irrelevant

17
Perl Basic syntax (cont.)

• Variable types
• Scalars
• Arrays

18
Perl Basic syntax (cont.)

• Variable types
• Arrays

19
Perl Basic syntax (cont.)

• Variable types
• Hashes

20
Perl Basic syntax (cont.)

• Variable scoping
• Conditional constructs

21
Perl Basic syntax (cont.)

• Conditional constructs
• While

22
Perl Basic syntax (cont.)

• for
• foreach

23
Perl Basic syntax (cont.)

• Operators
• Arithmetic
• Numeric comparison

24
Perl Basic syntax (cont.)

• Operators
• String comparison
• Boolean logic

25
Perl Basic syntax (cont.)

• Files and IO

26
Perl Basic syntax (cont.)

• String matching

27
Perl Basic syntax (cont.)

• String matching

28
Perl Basic syntax (cont.)

• Subroutines

29
CGI environment variables (ENV)
30
CGI environment variables (ENV)

• example- Printing environment variables
• !/usr/bin/perl
• use strict
• use CGI qw(standard)
• use CGICarp qw(warningsToBrowser
  fatalsToBrowser)
• print header
• print start_html("Environment")
• foreach my key (sort(keys(ENV)))
• print "key ENVkeyltbrgt\n"
• print end_html

31
CGI environment variables (ENV)

• Example- Referrer
• !/usr/bin/perl
• use strict
• use CGI qw(standard)
• use CGICarp qw(warningsToBrowser
  fatalsToBrowser)
• print header
• print start_html("Referring Page")
• print "Welcome, I see you've just come from
  ENVHTTP_REFERER!ltpgt\n"
• print end_html

32
CGI environment variables (ENV)

• Example- Browser detection
• !/usr/bin/perl
• use strict
• use CGI qw(standard)
• use CGICarp qw(warningsToBrowser
  fatalsToBrowser)
• print start_html("Browser Detect")
• my(ua) ENVHTTP_USER_AGENT
• print "User-agent ualtpgt\n"
• if (index(ua, "MSIE") gt -1)
• print "Your browser is Internet Explorer.ltpgt\n"
  
• elsif (index(ua, "Netscape") gt -1)
• print "Your browser is Netscape.ltpgt\n"
• elsif (index(ua, "Safari") gt -1)
• print "Your browser is Safari.ltpgt\n"
• elsif (index(ua, "Opera") gt -1)
• print "Your browser is Opera.ltpgt\n"
• elsif (index(ua, "Mozilla") gt -1)

33
Form processing
34
Form processing (cont.)

• !/usr/bin/perl
• use CGI qw(standard)
• use CGICarp qw(warningsToBrowser
  fatalsToBrowser)
• use strict
• print header
• print start_html("Thank You")
• print h2("Thank You")
• my form
• foreach my p (param())
• formp param(p)
• print "p formpltbrgt\n"
• print end_html

35
Form processing (cont.)

• !/usr/bin/perl
• use CGI qw(standard)
• use CGICarp qw(warningsToBrowser
  fatalsToBrowser)
• use strict
• print header
• print start_html("Results")
• Set the PATH environment variable to the same
  path
• where sendmail is located
• ENVPATH "/usr/sbin"
• open the pipe to sendmail
• open (MAIL, "/usr/sbin/sendmail -oi -t") or
  dienice("Can't fork for sendmail !\n")
• change this to your own e-mail address
• my recipient 'nullbox_at_cgi101.com'

36
Form processing (cont.)

• Start printing the mail headers
• You must specify who it's to, or it won't be
  delivered
• print MAIL "To recipient\n"
• From should probably be the webserver.
• print MAIL "From nobody\_at_cgi101.com\n"
• print a subject line so you know it's from your
  form cgi.
• print MAIL "Subject Form Data\n\n"
• Now print the body of your mail message.
• foreach my p (param())
• print MAIL "p ", param(p), "\n"
• Be sure to close the MAIL input stream so that
  the
• message actually gets mailed.
• close(MAIL)

37
Form processing (cont.)

• Now print a thank-you page
• print ltltEndHTML
• lth2gtThank Yoult/h2gt
• ltpgtThank you for writing!lt/pgt
• ltpgtReturn to our lta href"index.html"gthome
  pagelt/agt.lt/pgt
• EndHTML
• print end_html
• The dienice subroutine handles errors.
• sub dienice
• my(errmsg) _at__
• print "lth2gtErrorlt/h2gt\n"
• print "ltpgterrmsglt/pgt\n"
• print end_html exit

38
Setting cookies

• !/usr/bin/perl
• use strict
• my cid int(rand(1000000))
• print "Set-Cookie NAMEcid\n"
• print "Content-type text/html\n\n"
• print ltltEndOfHTML lthtmlgtltheadgtlttitlegtWelcomelt/tit
  legtlt/headgt ltbodygt lth2gtWelcome!lt/h2gt Your cookie
  is cid.ltpgt lt/bodygtlt/htmlgt
• EndOfHTML

39
Reading cookies

• !/usr/bin/perl
• use CGI qw(standard)
• use CGICarp qw(warningsToBrowser
  fatalsToBrowser)
• use strict
• print header()
• print start_html("Cookie")
• print h2("Welcome!")
• if (my cookie cookie('mycookie'))
• print "Your cookie is cookie.ltbrgt"
• else
• print "You don't have a cookie named
  mycookie'.ltbrgt"
• print end_html

40
References

• http//httpd.apache.org/docs/1.3/howto/ssi.html
• http//learn.perl.org/
• http//www.stanford.edu/class/cs193i/handoutsSum20
  04/21CGI.pdf
• http//www.stanford.edu/class/cs193i/handoutsSum20
  04/22CGI2.pdf
• http//www.stanford.edu/class/cs193i/handoutsSum20
  04/23CGI3.pdf

41
LAMP
42
What is LAMP?

• LAMP refers to a set of tools
• Linux
• Apache
• MySQL
• PHP
• It allows for rapid deployment of software
  applications
• It can be defined as Open Source platform
• We have already discussed on Linux and Apache
• We should talk more about PHP and MySQL

43
PHP overview

• Open Source server-side scripting language
  designed specifically for the web.
• In-line scripting
• Conceived in 1994, now used on 10 million web
  sites. Now in version 5.0
• Outputs not only HTML but can output XML, images
  (JPG PNG), PDF files and even Flash movies
  (using libswf and Ming) all generated on the fly.
  Can write these files to the filesystem.
• Supports a wide-range of databases (inherently or
  via ODBC).
• PHP also has support for talking to other
  services using protocols such as LDAP, IMAP,
  SNMP, POP3, HTTP.
• Supports OO programming
• Perl- and C-like syntax. Relatively easy to
  learn.
• Website _at_ http//www.php.net/

44
Why use PHP

• If you like free software or need a free solution
• If you need a solution thats portable across
  multiple platforms (e.g. Red Hat Linux to Windows
  2000)
• If you want to add dynamic content to your pages
• If you want to make your pages easier to maintain
• There are a lot of open source/free
  packages/libraries available in PHP.
• Many mailing lists/sites are dedicated to it.
• Examples of uses of PHP
• Small/Medium Portals
• Small/Medium Web-Mails
• Content Management

45
What is in a php file

• PHP files may contain text, HTML tags and scripts
• PHP files are returned to the browser as plain
  HTML
• PHP files have a file extension of ".php",
  ".php3", or .phtml
• Embedding PHP in HTML
• lthtmlgt
• ltbodygt
• ltstronggtHello World!lt/stronggtltbr /gt
• lt?
• echo This is a PHP introductory course!
• ?gt
• lt/bodygt
• lt/htmlgt

46
Include mechanism

• lt?php
• include '../includes/header.html'
• ?gt
• ltcentergt
• content of your web page
• lt/centergt
• lt?php
• include 'http//cs.ucy.ac.cy/php/footer.html'
• ?gt
• Content can be included from a local or remote
  source via such protocols as HTTP, HTTPS, FTP,
  and FTPS

47
Types

• Scalar types
• Boolean
• Integer
• Float
• String
• Compound types
• Array
• Object

48
Variables

• Variables all start with a
• Case-sensitive
• Must start with a letter or underscore, followed
  by any number of letters, numbers, or underscores
• Variables are not explicitly typed
• Type of value is inferred on operator application
• Uninitialized variables have value undef
• What undef means depends on context
• Numeric context it is 0
• String context it is empty string

49
Variables

• To assign values to variables
• foo bar Data Type String
• foo 1 Data Type integer
• foo 5.34 Data Type float
• foo array(bar,united) Data Type Array
• Data Types are automatically assigned though you
  can force a data type by type casting. For
  example
• foo Hello
• bar (int)foo
• bar now equals 0
• Almost all variables are local (page). Global
  variables include _Session

50
Example

• lthtmlgt
• ltbodygt
• ltpgt lt?php
• temperature 5
• conversionFactorC2K 273
• print("temperature degC")
• echo " is "
• print(temperatureconversionFactorC2K."degK")
  ?gt
• lt/pgt
• lt/bodygt
• lt/htmlgt

51
Associative arrays

• Java arrays are indexed by number, e.g. a0
• PHP arrays can also be indexed by association,
• e.g.
• phone'mark''3497'
• phone'ian''3098'
• peoplearray_keys(phone)
• foreach (people as person)
• echo "person is on ext ".phoneperson."ltbr
  /gt"

52
Arrays

• Actually an ordered map
• So you can use it like a vector, hashtable,
  dictionary, stack, queue etc.
• May contain other arrays
• You could build trees with them
• In fact, they can contain any PHP type
• They are dynamic (their size is changing at
  runtime)

53
Array Syntax

• Creation with array()
• lt?php
• arr array("foo" gt "bar", 12 gt true)
• echo arr"foo"
• echo arr12
• ?gt

54
Array of array

• lt?php
• arr array(
• "somearray" gt array(6 gt 5, 13 gt 9, "a" gt
• 42))
• echo arr"somearray"6 // 5
• echo arr"somearray"13 // 9
• echo arr"somearray""a" // 42
• ?gt

55
Parameters

• Pass by value is default
• lt?php
• function addNothing(string)
• string . with a cherry on top.
• dessert Ice cream
• addNothing(dessert)
• echo dessert
• ?gt

56
Parameters

• By reference
• lt?php
• function addTopping(string)
• string . with a cherry on top.
• dessert Ice cream
• addTopping(dessert)
• echo dessert
• ?gt

57
Servers variable array

• _SERVER is an array containing information
• such as
• Headers
• Paths
• Script locations
• The entries in this array are created by the
  webserver. There is no guarantee that every
  webserver will provide any of these servers may
  omit some, or provide others

58
Servers variable array
59
Server variables

• 'argv'
• Array of arguments passed to the script. When the
  script is run on the command line, this gives
  C-style access to the command line parameters.
  When called via the GET method, this will contain
  the query string.
• 'argc'
• Contains the number of command line parameters
  passed to the script (if run on the command
  line).

60
Server variables

• 'REMOTE_ADDR'
• The IP address from which the user is viewing the
  current page.
• 'REMOTE_HOST'
• The Host name from which the user is viewing the
  current page.
• 'REMOTE_PORT'
• The port being used on the user's machine to
  communicate with the web server.

61
HTML Forms

• When a form is submitted to a PHP script, the
  information from that form is automatically made
  available to the script
• Theres a few ways to do this
• Example
• ltform action"foo.php" method"POST"gt
• Name ltinput type"text" name"username"gtltbrgt
• Email ltinput type"text" name"email"gtltbrgt
• ltinput type"submit" name"submit"
  value"Submit"gt
• lt/formgt

62

• lthtmlgtltbodygtltpgt
• lt?php
• print _POST'username'
• ?gt
• lt/pgtlt/bodygtlt/htmlgt
• _GET
• _REQUEST
• _FILES An associative array of items uploaded
  to the current script via the HTTP POST method.

63
Session

• _SESSION
• An associative array containing session variables
  available to the current script.
• A way to preserve certain data across subsequent
  accesses
• Loads of session handling functions
• name, lifetime, cache etc.

64
Session

• The idea of a session is to track a user during a
  single session on a web site. This enables
  customized web pages, single login during a
  session, shopping cart applications, and tracking
  users behavior
• Cryptographically generated to be a unique
  session id
• Session ID is stored as a cookie on the client
  box or passed along through URL's.
• Session variable values are stored in the
  'superglobal associative array '_SESSION.'
• The values are actually stored at the server and
  are accessed via the session id from your cookie.
• On the client side the session ID expires when
  connection is broken.

65
Session handling example

• Page 1
• lt?php
• session_start()
• _SESSIONFName' _GetFName'
• _SESSIONLName' _GetLName'
• include '../includes/header.html'
• ?gt
• Page 2
• lt?php
• session_start()
• echo _SESSIONFName' . .
  _SESSIONLName'
• ?gt

66
Cookies

• Cookies are little text file that a web site
  stores in the clients computer to maintain
  information about that client
• Cookies are sent along with the rest of the HTTP
  headers
• Like other headers, cookies must be sent before
  any output from your script (this is a protocol
  restriction).
• This requires that you place calls to this
  function prior to any output, including lthtmlgt
  and ltheadgt tags

67
Cookies

• Setting a cookie
• setcookie(TestCookie", lngen)
• Setting a cookie with expiration
• setcookie("TestCookie", lngen, time()3600)
  / expire in 1 hour /
• Access and print a cookie
• echo _COOKIETestCookie
• Delete a cookie
• setcookie ("TestCookie", "", time() - 3600)
• set the expiration time to an hour ago

68
PHP and MySQL

• PHP and MySQL are a perfect companion
• Largely because they are both free and they have
  numerous capabilities
• PHP as of version 3 supports inherently MySQL
  i.e. specialized build-in functions handle the
  database interactions
• Same goes with ORACLE but not with Microsoft
  databases (Access, SQL Server)

69
Example

• lthtmlgt
• ltbodygt
• lth1gtA List of Users Who Have Signed Up For
  .lt/h1gt
• lt?
• dbh mysql_connect("localhost",dbusername",dbp
  assword")
• or die(Couldn't connect to database.")
• db mysql_select_db(dbname", dbh)
• or die(Couldn't select database.")
• sql SELECT username, email FROM userspool
• result mysql_query(sql)
• or die(Something is wrong with your SQL
  statement.")
• while (row mysql_fetch_array(result))
• username rowusername
• email rowemail
• echo lta hrefmailto.email.gt.username.lt/
  agtltbr /gt
• ?gt
• lt/bodygt
• lt/htmlgt

70
MySQL
71
What is MySQL?

• SQL Structured Query Language
• MySQL is a open-source, multithreaded,
  multi-user, SQL (Structured Query Language)
  relational database server
• MySQL works on many different platformsincluding
  FreeBSD, UNIX, Linux, Mac OS X, OS/2 Warp,
  Solaris, SunOS, SCO, Windows, and other OSs.¹
• MySQL is used by companies like The Associated
  Press, Google, NASA, Sabre Holdings, American
  Greetings, and Suzuki.²

72
Relational Database

• Basically information organized in a structure.
• Top level
• Database (Excel File)
• -gt Tables (Excel Sheet)
• -gt Columns and Rows
• -gt Data
• Therefore data is organized into categories which
  can be stored and retrieved in an efficient
  manner as long as you know where to look.

73
Programming Languages

• Programming languages which can access MySQL
  databases include C, C, Eiffel, Smalltalk,
  Java, Lisp, Perl, PHP, Python, Ruby, and Tcl.²
• You need to either compile in MySQL support when
  installing these languages or have access to
  MySQL libraries respective to the programming
  language (i.e. libMySQL.dll)

74
Installation and Setup

• Download installation package or source/rpms from
  www.mysql.com.
• Run setup utility/install rpms/compile from
  source.
• Setup administrator access using mysqladmin.
  This command allows you to setup root access and
  run administrative commands from the command
  prompt.
• Login to MySQL daemon
• Windows c/mysql/bin/mysql u username p h
  host
• nix mysql u username p h host
• Use root user to add new users with privileges.

75
Setup Users

• Privileges can be granted at four levels
• Global level
• Global privileges apply to all databases on a
  given server. These privileges are stored in the
  mysql.user table. GRANT ALL ON . and REVOKE ALL
  ON . grant and revoke only global privileges.
• Database level
• Database privileges apply to all tables in a
  given database. These privileges are stored in
  the mysql.db and mysql.host tables. GRANT ALL ON
  db_name. and REVOKE ALL ON db_name. grant and
  revoke only database privileges.²
• Table level
• Table privileges apply to all columns in a given
  table. These privileges are stored in the
  mysql.tables_priv table. GRANT ALL ON
  db_name.tbl_name and REVOKE ALL ON
  db_name.tbl_name grant and revoke only table
  privileges.
• Column level
• Column privileges apply to single columns in a
  given table. These privileges are stored in the
  mysql.columns_priv table. When using REVOKE, you
  must specify the same columns that were granted.

76
Setup Users

• So a command to grant user to database test
• GRANT ALL PRIVILEGES ON test. TO
  user_at_'localhost' IDENTIFIED BY password
• Then we need to reload the privileges
• FLUSH PRIVILEGES
• Thus user may access the MySQL database from
  localhost (server) on all tables in the test
  database.
• mysql u user p
• password password

77
Creating Databases

• Syntax
• create database databasename
• create database library
• Then we can see the database
• show databases
• -------------------
• library
• test
• -------------------
• Then we need to access/use the databse
• use library

78
Creating Tables

• Syntax
• CREATE TABLE tablename (
• column1 attributes,
• column2 attributes,
• column3 attributes)
• CREATE TABLE books (
• book_id INT(4) PRIMARY KEY NOT NULL
  AUTO_INCREMENT UNSIGNED,
• title VARCHAR(255),
• author VARCHAR(255),
• location VARCHAR(32),
• ISBN VARCHAR(16),
• quantity INT DEFAULT 0)

79
Creating Tables Cont

• We can then see what tables are in a database
• Show tables
• -------------------
• Tables_in_library
• -------------------
• books
• -------------------
• Then we can see what columns are in a table.
• DESCRIBE (DESC) tablename
• DESC TABLE books
• ---------------------------------------------
  -------------------
• Field Type Null Key
  Default Extra
• ---------------------------------------------
  -------------------
• book_id int(4) unsigned PRI
  NULL auto_increment
• title varchar(255) YES NULL
  
• author varchar(255) YES NULL
  
• location varchar(32) YES NULL
  
• ISBN varchar(16) YES NULL
  

80
Insert Rows

• Syntax
• INSERT (IGNORE) INTO tablename (columns to
  insert) VALUES (values to insert)
• INSERT INTO books (title, author, location)
  VALUES ("The Hobbit", "JRR Tolkien", F Tolkien,
  J)
• INSERT INTO books (title, author, location,
  ISBN, quantity) VALUES (Windows XP", William
  Gates", 115.4, 1282105242142943, 1)
• Notice I did not specify a book_id, this is
  because it is an auto incrementing row.
  Therefore The Hobbit will be book_id 1, and
  Windows XP will be book_id 2.

81
Selecting Rows

• Syntax
• SELECT columns FROM tablename WHERE condition
• SELECT title, author FROM books WHERE book_id
  1
• -------------------------
• title author
• -------------------------
• The Hobbit JRR Tolkien
• -------------------------
• If you do not specify a WHERE clause, it will
  select EVERYTHING
• SELECT title, author FROM books
• ---------------------------
• title author
• ---------------------------
• The Hobbit JRR Tolkien
• Windows XP William Gates
• ---------------------------

82
Selecting Rows Cont

• If you want to rename the returned column, use an
  as
• SELECT title as what, author as who FROM books
• ---------------------------
• what who
• ---------------------------
• The Hobbit JRR Tolkien
• Windows XP William Gates
• ---------------------------
• The wildcard can be used to select all
  columns
• SELECT FROM books
• ----------------------------------------------
  --------------------------------
• book_id title author location
  ISBN quantity
• ----------------------------------------------
  --------------------------------
• 1 The Hobbit JRR Tolkien F
  Tolkien, J NULL 0
• 2 Windows XP William Gates 115.4
  1282105242142943 1
• ----------------------------------------------
  --------------------------------

83
Selecting Count

• Count is a special syntax which returns a
  numerical amount of a select statement
• SELECT COUNT() FROM books
• ----------
• COUNT()
• ----------
• 2
• ----------
• Distinct is another syntax which returns unique
  values of a select statement
• SELECT DISTINCT author FROM books

84
Updating Rows

• Updating rows changes values of data within rows.
• Syntax
• UPDATE tablename SET attribute1 value1,
  attribue2 value2 WHERE conditions
• UPDATE books SET quantity 5 WHERE book_id 1
• SELECT FROM books WHERE book_id 1
• ----------------------------------------------
  ------------------
• book_id title author location
  ISBN quantity
• ----------------------------------------------
  ------------------
• 1 The Hobbit JRR Tolkien F Tolkien,
  J NULL 5
• ----------------------------------------------
  ------------------
• WARNING! Be careful of update statements and to
  specify a WHERE clause. Without a WHERE clause,
  all rows will be updated with quantity of 5.

85
Deleting Rows

• Syntax
• DELETE FROM tablename WHERE conditions
• DELETE FROM books WHERE book_id 2
• SELECT FROM books
• ----------------------------------------------
  ------------------
• book_id title author location
  ISBN quantity
• ----------------------------------------------
  ------------------
• 1 The Hobbit JRR Tolkien F Tolkien,
  J NULL 5
• ----------------------------------------------
  ------------------
• WARNING! Be careful of delete statements and to
  specify a WHERE clause. Without a WHERE clause,
  all rows will be deleted. If you need to delete
  all the contents of a table
• DELETE FROM books
• However, this does not reset the indexes of a
  table, therefore a better command is
• TRUNCATE books

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Where Clauses

• Where clauses are very important to select,
  update, and delete statements.
• Where clauses can be in multiple formats and
  contain multiple parameters
• WHERE number (NOT) IN (0,1,2)
• WHERE (book_id 1 AND ISBN IS (NOT) NULL) OR
  location 0
• WHERE (date gt 10212004) AND (date lt 11222004)
• WHERE (quantity 2) 4
• Where clauses can be quite long and complex, as
  the programmer you need to know how to read them
  as well as script them.

87
Altering Tables

• Altering tables enables you to change the
  structure of a table, whether it be changing
  default values to removing or adding columns.
• ALTER (IGNORE) TABLE tablename
  alter_specification
• ALTER TABLE books ADD date timestamp
• ALTER TABLE books RENAME catalog
• ALTER TABLE books MODIFY author INT(11) NOT
  NULL
• ALTER TABLE books CHANGE ISBN price float
• ALTER TABLE books DROP COLUMN quantity

88
Drop Statements

• Drop syntax deletes entire tables or databases.
• DROP TABLE tablename
• DROP TABLE books
• DROP databasename
• DROP library
• This is for deleting databases and tables, not
  just clearing the entries!

89
More on Selects

• Select Statements can be used for multiple
  tables
• Example
• SELECT author_id FROM authors WHERE lastname
  LIKE Rawling
• -----------
• author_id
• -----------
• 1029
• -----------
• SELECT title FROM books WHERE author_id 1029
• -----------------------------------------
• Title
• -----------------------------------------
• Harry Potter and the Sorcerer's Stone
• Harry Potter and the Chamber of Secrets
• -----------------------------------------

90
More on Selects

• Instead of doing two queries, combine them
• SELECT b.title FROM authors a, books b WHERE
  b.author_id a.author_id AND a.lastname LIKE
  Rawling
• -----------------------------------------
• Title
• -----------------------------------------
• Harry Potter and the Sorcerer's Stone
• Harry Potter and the Chamber of Secrets
• -----------------------------------------
• Even better, we can use a left join
• SELECT b.title FROM books LEFT JOIN authors ON
  b.author_id a.author_id WHERE a.lastname LIKE
  Rawling
• Joins are generally better.
• This can also be applied to multiple UPDATES and
  DELETES.

91
Indexes

• What are indexes?
• When talking about databases, indexing is a
  technique used by most current database
  management systems to speed up particular kinds
  of queries (usually by internally generating and
  storing redundant information to more quickly
  locate table entries).
• For integers, strings, and text, this is
  invaluable! Especially if the size of the table
  is large!

92
Creating Indexes

• Syntax
• CREATE (UNIQUEFULLTEXTSPATIAL) INDEX
  index_name (index_type) ON tablename
  (column1,column2,)
• CREATE INDEX isbn_index ON books (ISBN)
• You can specify a certain amount to index on,
  especially helpful with strings
• CREATE INDEX title_index ON books (title(11))
• Unique indexes help prevent duplicate entries
• CREATE UNIQUE INDEX author_lastname ON author
  (lastname(11))
• You can assign an index to multiple columns to
  prevent duplicate entries
• CREATE UNIQUE INDEX author_ref ON books (title,
  authorid)

93
Creating Tables With Indexes

• Syntax
• CREATE TABLE tablename (
• column1 attributes,
• KEY index_name (column(size))
• )
• CREATE TABLE books (
• book_id INT(4) PRIMARY KEY NOT NULL
  AUTO_INCREMENT UNSIGNED,
• title VARCHAR(255),
• author VARCHAR(255),
• KEY title_index (title(11)),
• KEY author_index (author(11)),
• )
• Note book_id does not need an index since
  primary key attribute takes care of it.

94
Dropping Indexes

• Syntax
• DROP INDEX index_name ON tablename
• DROP INDEX author_index ON books

95
MySQLdump

• MySQLdump is a command which dumps defined
  contests of a database. This is handy in terms
  of backups
• Syntax
• mysqldump u username p (databasename)
  (tablename)
• Useful flags
• -A--all-databases dumps all databases
• -a--all same as previous
• -c--complete-insert use complete insert
  statements
• -e--extended-insert use extended insert
  statements
• --add-drop-table add a drop table before
  each create table syntax
• -h--host define a host
• -n--no-create-db do not specify a create
  database command
• -d--no-data do not include the data
• -P--port
• --tables

96
MySQLdump

• A method of backing up a entire database in nix
  is
• mysqldump u username p database gt date.sql
• Mysqldump exports to the console screen, so it is
  useful to pipe it into a file, no idea how to do
  this in MSDOS.
• There are two ways to restore a backup to mysql
• 1. Pipe data back into mysql server
• mysql u username p databasename lt file
• mysql u user p library lt date.sql
• 2. Source data from within mysql server
• source filename
• source date.sql

97
References

• http//php.net
• http//mysql.com
• http//www.wikipedia.net
• http//www.mysql.com
• https//ims.ecn.purdue.edu/documentation.html