MCIS/UA PHP Training 2003 Chapter 5 Object Oriented Concepts - - PowerPoint PPT Presentation

PHP Training 2003 Chapter 5 Object Oriented Concepts Datasource/Database Classes

MCIS/UA

OOP myth

• OOP has NOTHING to do with graphics
• r graphical user interfaces (GUIs).

scenario

Why OOP?

• Imagine the following scenario...
• The year is 2007
• Miami is currently running Banner version 9.1.5
• PHP has taken root and we now have 12,000

PHP files and applications.

• You read your email and find that Banner version

10.0 has been released

• One of the "features" is that SPBPERS is being

split into 5 separate tables

→

Why OOP?

• Scenario #1
• 7,000 of the 12,000 PHP files have to be

modified to account for this change.

• Scenario #2
• 5 of the 12,000 PHP files have to be modified to

account for this change.

real life scenario

Why OOP?

• Real life scenario...
• The year is 2003
• We've deployed 83+ Cold Fusion applications

that authenticate via LDAP

• The LDAP authentication code was copied from

program to program

• Next month, Technical Services is changing the

way LDAP works.

→

Why OOP?

• Scenario #1
• Fix 83+ Cold Fusion programs in the next month
• Scenario #2
• Fix 1 library that all programs are using to do

authentication

• Scenario #3
• Fix 1 library that all programs are using to do

authentication AND add single-signon capabilities to all of them

intro

Why OOP?

• Think about an application that you wrote

recently...

• Did you write any code that exists in another

application?

• Did you reuse that code (not a copy...but the

actual code)?

• How much work would it take to make a major

change to that program?

• For example, switching from using an array or

flat file to using a database?

• Or splitting a single database table into 5?

intro

OOP Introduction

• OOP is an evolutionary step in the history
• f programming concepts

Spaghetti Code ↓ Modular Programming ↓ Structured Programming ↓ Object Oriented Programming

→

OOP Introduction

• OOP is designed to facilitate the following:
• Code Reuse - goal is 0% code duplication
• Easier Development (especially for large

projects)

• Distributed Development
• Increased Quality
• Better model the real world
• Easier Maintenance and Enhancement

→

OOP Introduction

• OOP requires a rethinking of code design
• Tying the data and the operations

performed on that data together into an

• bject
• Typically, data is hidden from all but the
• bject itself - blackbox approach
• You may already be using many of the

concepts and you don't know it

int example

Conceptual Example

• Integer
• Value

5, -27, 0, etc.

• Actions:

Creation Assignment Addition, Subtraction, Multiplication, etc. Retrieval

→

Conceptual Example

• How are integers stored internally?
• in memory?
• in registers?
• swapped out on disk?
• What would happen to your code if the

next version of the compiler changed the way integers were stored?

• 32-bit to 64-bit?

→

Conceptual Example

terminology

Creation int $i;

(not required in PHP)

Assignment $i = 5; Operations $i + 3; Retrieval print $i; person $p; $p's name is "Mary Smith" Generate bill for $p print $p;

OOP term Description

int $i; $i = 5; $i + 5; Person $p; $p's name is Mary generate $p's bill

Class The "data type" int Person Object / Instance An instance of the data type $i $p Property/ attribute data associated with the object integer value (5) name (Mary) Method functions associated with the object + generate bill

OOP Terminology

→

OOP Terminology

• Encapsulation
• Hiding the internal data structures from

the rest of the program

• Allows the internal data structures to

change without recoding the program.

• Blackbox approach
• For Person, instead of accessing the name

directly, use getName() and setName().

→

OOP Terminology

• Inheritance
• Creating a new class that is an extension
• f another class

db class

undergraduate student → graduate person → classified employee → unclassified

Datasource/Database Classes

• As an example of using OOP

, I will be demonstrating the Datasources and Database classes.

• Used to access databases (and other

resources)

• Designed to be relatively database independent
• Oracle
• mySQL

→

Datasource/Database Classes

• Written in-house by Net Apps
• Documented at:

http://webdev.admin.muohio.edu/phpapps/envdocs/ info table

Info Table

datasources

UniqueId Name Address Phone covertka Kent Covert 352 Gaskill 529-7317 kingmatm Tim Kingman 354 Gaskill 529-5330 moosejc John Moose 354 Gaskill 529-1427 tepeds Dirk Tepe 357 Gaskill 529-1514

Datasources

• Similar to datasources in Cold Fusion, but

expanded

• Datasources are used to access certain resources

(e.g. databases, LDAP , etc.)

• Datasources allow developers to access resources

without hardcoding usernames, passwords, database instances into their applications.

• Datasources allow data admin to change resource

characteristics without modifying applications.

→

Datasources

• Datasources are/will be created by Data

Admin

• Datasources are referenced by name

→

Datasources

• Database datasources:
• contain
• database type (Oracle, mySQL, etc.)
• host
• port
• database instance (PROD, MUCC, etc.)
• username and password

creating instances

Creating a new instance

• New instances of a class can be

created using the new keyword. $instance = new className(...);

• Creates a new instance of the class

"className"

• The new instance is returned as a reference

(and is stored in $instance in this example)

• This reference ($instance) is used for all

future interaction with this instance

→

Creating a new instance

$info = new DataSource("info");

$prod = new DataSource("Prod");

$time = new DataSource("TimeEntry");

methods

Calling Methods

• Methods and attributes are accessed by using

the -> operator.

$instance->methodName(parameters, ...)

• This will call the methodName method of the

$instance instance.

$info = new DataSource("info"); $time = new DataSource("timeEntry"); perform

perform database method

• The perform() method can be used to issue

simple SQL (non-select) queries.

$info = new DataSource("info"); $info->perform("DELETE FROM info " . "WHERE uniqueId = 'covertka'");

• Returns true on success, false otherwise

bad

perform database method

$uniqueId = $_REQUEST["uniqueId"]; $info->perform("DELETE FROM info " . "WHERE value = '$uniqueId'"); print $uniqueId; ' OR '' = ' $info->perform("DELETE FROM info " . "WHERE uniqueId = '' OR '' = ''"); placeholders

perform database method

$info = new DataSource("info"); $uniqueId = 'covertka'; $info->perform("DELETE FROM info " . "WHERE uniqueId = ?", $uniqueId); $info->perform("DELETE FROM info " . "WHERE uniqueId = '\' OR \'\' = \''"); commit

commit database method

• The commit() method can be used to

commit database changes

$info = new DataSource("info"); $info->perform("DELETE FROM info " . "WHERE uniqueId = ?", $uniqueId); $info->commit();

• Available for all databases but doesn't

necessarily do anything (database dependent)

rollback

rollback database method

• The rollback() method can be used to undo

database changes

$info = new DataSource("info"); $info->perform("DELETE FROM info " . "WHERE uniqueId = ?", $uniqueId"); $info->rollback();

• Available for all databases but doesn't

necessarily do anything (database dependent)

rollback

Handling Selects

• Many methods for handling selects
• many of the differences are purely for

convenience

queryFirstColumn() queryFirstRow_array() queryFirstRow_assoc() queryAll_array() queryAll_assoc() prepare()

queryFirstColumn

queryFirstColumn()

• Used to access a single value from a select
• Returns the first column of the first row

$value = $dbh->queryFirstColumn($statement, ...); $info = new DataSource("info"); $name = $info->queryFirstColumn( "SELECT name ". "FROM info ". "WHERE uniqueid = 'covertka'"); print $name; → Kent Covert

→

queryFirstColumn()

$info = new DataSource("info"); $name = $info->queryFirstColumn( "SELECT name ". "FROM info ". "WHERE uniqueid = ?", $uid); print $name; → Kent Covert

queryFirstRow_array

queryFirstRow_array()

• Used to access a single row from a select
• Returns the first row as a numerically indexed

array

$array = $dbh->queryFirstRow_array($statement, ...);

→

queryFirstRow_array()

$info = new DataSource("info"); $row = $info->queryFirstRow_array( "SELECT name, address, phone ". "FROM info ". "WHERE uniqueid = ?", $uid); print $row[0]; → Kent Covert print $row[1]; → 340 Gaskill Hall print $row[2]; → 529-7317

queryFirstRow_assoc

queryFirstRow_assoc()

• Similar to queryFirstRow_array()
• Returns the first row as an associative array

$array = $dbh->queryFirstRow_assoc($statement, ...);

→

queryFirstRow_assoc()

$info = new DataSource("info"); $row = $info->queryFirstRow_assoc( "SELECT name, address, phone ". "FROM info ". "WHERE uniqueid = ?", $uid);

print $row['name']; → Kent Covert print $row['address']; → 340 Gaskill Hall print $row['phone']; → 529-7317

queryAll_array

queryAll_array()

• Returns all the rows of a select
• Returned as a numerically indexed array of

associative arrays

$array = $dbh->queryAll_array($statement, ...);

→

queryAll_array()

$info = new DataSource("info"); $rows = $info->queryAll_array( "SELECT uniqueId, name, address, phone ". "FROM info"); print $rows[0]['name']; → Kent Covert print $rows[3]['name']; → Dirk Tepe print $rows[3]['uniqueId']; → tepeds

queryAll_assoc

queryAll_assoc()

• Returns all the rows of a select
• Returned as an associative array of associative

arrays keyed on the first column of the result

$array = $dbh->queryAll_assoc($statement, ...);

→

queryAll_assoc()

$info = new DataSource("info"); $rows = $info->queryAll_assoc( "SELECT uniqueId, name, address, phone ". "FROM info");

print $rows['covertka']['name']; → Kent Covert print $rows['tepeds']['name']; → Dirk Tepe print $rows['tepeds']['uniqueId']; →

prepare

prepare()

• Allows custom handling of result sets
• Handles repeated queries easily

$sth = $dbh->prepare($statement);

• Notice no placeholders - handled when

executed

• Returns a statement handle object, or false on

error

prepare example

prepare()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?");

statement handle

Statement Handle Class

• Used to repeatedly execute the same

statement with different values

• Loop over the rows returned by a select

execute() fetchRow_array() fetchRow_assoc() seek_forward() free() current_row attribute

execute

Statement Handle execute()

• Executes a previously prepared statement

$sth->execute(placeholders);

• Returns true on success, false otherwise

execute example

Statement Handle execute()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "354 Gaskill Hall"; $sth->execute($address); . . . $address = "352 Gaskill Hall"; $sth->execute($address);

fetchRow_array()

Statement Handle fetchRow_array()

• Fetches the next row in the result set as a

numerically indexed array

• Repeated calls fetch the next row until none

are left

$array = $sth->fetchRow_array();

• Returns false when no rows left

fetchRow_array example

Statement Handle fetchRow_array()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "354 Gaskill Hall"; $sth->execute($address); while($row = $sth->fetchRow_array()) { print $row[1]; } Tim Kingman John Moose

another execute

Statement Handle fetchRow_array()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "354 Gaskill Hall"; $sth->execute($address); while($row = $sth->fetchRow_array()) { print $row[1]; } $address = "352 Gaskill Hall"; $sth->execute($address); while($row = $sth->fetchRow_array()) { print $row[1]; }

fetchRow_assoc

Statement Handle fetchRow_assoc()

• Similar to fetchRow_array()
• Returns associative array rather than a

numerically indexed array

$array = $sth->fetchRow_assoc();

• Returns false when no rows left

fetchRow_assoc example

Statement Handle fetchRow_assoc()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "354 Gaskill Hall"; $sth->execute($address); while($row = $sth->fetchRow_assoc()) { print $row['name']; } Tim Kingman John Moose

current_row

Statement Handle current_row attribute

• The current_row attribute contains the

number of the row about to be fetched

• Starts at 1

$row = $sth->current_row;

• Notice that there are no (). This is an attribute
• not a function.
• Contains false when no rows left

current_row example

Statement Handle current_row attribute

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "352 Gaskill Hall"; $sth->execute($address); print $sth->current_row; → 1 print $sth->fetchRow_assoc(); → Array print $sth->current_row; → 2 print $sth->fetchRow_assoc(); → false print $sth->current_row; → false

seek_forward

Statement Handle seek_forward()

• The seek_forward() method can be used to

move forward in the result set

• It cannot move backwards through the result

set

$sth->seek_forward($row);

seek_forward example

Statement Handle seek_forward()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "354 Gaskill Hall"; $sth->execute($address); $sth->seek_forward(2); $row = $sth->fetchRow_assoc(); print $row['name']; John Moose

db cleanup

DB Cleanup

• All Statement Handles should be disposed of

using the free() method.

$sth->free();

• All database handles should be disposed of

using the disconnect() method.

$dbh->disconnect();

db cleanup example

Statement Handle seek_forward()

$info = new DataSource("info"); $sth = $info->prepare( "SELECT uniqueId, name, address, phone ". "FROM info ". "WHERE address = ?"); $address = "354 Gaskill Hall"; $sth->execute($address); $row = $sth->fetchRow_assoc(); print $row['name']; $sth->free(); $info->disconnect();

bind_by_name method

Bind_by_name method

• The Statement Handle method

bind_by_name() is used to bind PHP variables to named variables in SQL statements.

• Used with stored procedures
• Oracle specific

$sth->bind_by_name($placeholder_name, $variable[, $length]);

• See example in the documentation

questions

Questions?

Homework #5