Accelerating PHP development

Data-tier programmingBrian RosenthalZvi BoshernitzanRobocommerce

Overview: Data modeling

High-level approach to database design. We will describe

Basic principles of data modeling PHP Programming techniques

Database abstractions Stack-based database programming Inference-based database programming

Basic principles of data modeling Normalization: “Don’t repeat yourself.” Entity Relation “ER” diagrams

Normalization“Don’t Repeat Yourself” First approach: store

the author information within the book.

Problem: what if there is more than one author. Where do we store the second author?

-title-isbn-author_first_name-author_last_name

Books

Normalization“Don’t Repeat Yourself” Second approach:

store up to three authors

Problems: what if there are more, and what about all of the information about the authors (address, etc.)

-title-isbn-author1_first_name-author1_last_name-author2_first_name-author2_last_name-author3_first_name-author3_last_name

Books

Normalization“Don’t Repeat Yourself” Third approach: have

two tables: books and authors.

Authors have a book id.

“Each book may be written by 0 or more authors.”

Each author must be the writer of a book.

-title-isbn

Books

-book_id-first_name-last_name

Authors

-written by1

-writer of0..*

Normalization“Don’t Repeat Yourself”

Books

id title

1 Da Vinci Code

2 Angels and Demons

Authors

id book_id first_name last_name phone_number

1 1 Dan Brown 800-808-0808

2 2 Dan Brown 800-808-0808

Problem: We still have redundancy

Normalization“Don’t Repeat Yourself” Fourth approach:

have three tables: books, people, authorship.

Each entry in the “authorship” table is a fact. That a particular person participated in an authorship of a book

No information is repeated!

-title-isbn

Books-first_name-last_name-phone_number

Persons

-work of1

-of0..*

-book_id-author_id

Authorship

-participate in1

-of0..*

ER Diagrams This is an ER diagram. You read it: “Each product must be sold under a

brand” “Each brand may be the origin of 0 or more

products”category

product

brand

-category for1

-categorized by0..*

-origin of1

-sold under0..*

keyword

keyword_products

-indexed by1-for0..*

-indexed of1

-on0..*

PHP Database Infrastructure

Zvi: database abstractions. Brian: stack-based SQL programming Brian: inference-based SQL programming

Database “stack” programming SQL as a big string versus SQL as a “stack” SQL is, after all structured. {‘select’:’firstname,lastname’, ‘from’:’customers c’, ‘ijoin’:{‘s’:{‘table’:’sites’, ‘on’:’s.id = c.site_id’}}, ‘where’:[“c.name like ‘%brian%’”, “c.id > 10”], ‘limit’:10, ‘offset’:5} $q->add_where(…) $q->add_select(…), $q->set_select(…) $q->add_lojoin(…) $q->load_dict({‘select’:’c.address_id’, ‘where’:…}) $q->to_sql() $q->to_dict()

SPEC DRIVEN DATABASE PROGRAMMING db::objects($q->to_sql()) db::assocs($q->to_sql()) db::string($q->to_sql()) db::object($q->to_sql())

INFERENCE-BASED DATABASE PROGRAMMING A lot of information is stored in the database

schema The idea here is to use it where it is possible

to do so

Inferences from ER diagrams… if you were writing classes to manage these database entities, you might include:

products::mget_by_category(…) products::mget_by_brand(…) products::map_keyword(…) products::mget_by_keyword(…) keywords::mget_by_product(…)

category

product

brand

-category for1

-categorized by0..*

-origin of1

-sold under0..*

keyword

keyword_products

-indexed by1-for0..*

-indexed of1

-on0..*

Enter: PHP 5

Call handler override

“function __call($m, $args)” Mysql reflection Singleton / factory semantics Autoloads

You should really get all of these functions for free:

mg(‘products’)->get($product_id)

mg(‘products’)->create(‘name’, ‘lawnmower’)

mg(‘products’)->mget_by_keyword($keyword_id)

mg(‘products’)->mget_by_category($category_id)

mg(‘products’)->mget_by_brand($brand_id)

mg(‘products’)->get_by_sku($sku)

mg(‘products’)->get_title($product_id)

mg(‘products’)->get_title(‘sku’, $sku)

mg(‘products’)->map_keyword($keyword_id)

mg(‘products’)->colnames()

mg(‘categories’)->get_products($category_id)

So, here’s the class:class products extends dbentity {

function references() {

return array('brand_id' => 'brands‘, 'category_id' => 'categories');

}

function mappings() {

return array(

‘keywords' => array(‘product_keywords', 'product_id', ‘keyword_id', ‘keywords‘)

, ‘related_products' => array('product_relations', 'from_product_id', 'to_product_id', 'products')

, 'suppliers' => array('supplier_prices', 'product_id', 'supplier_id', 'suppliers‘

, array('wholesale_price' => 'price', 'sku' => 'sku'))

);

}

}

Customizing the sql:$q = new dbquery(array(

‘select’ => ‘p.name’

, ‘from’ => ‘products p’

, ‘ijoin’ => array(‘c’ => rba::_(‘table’, ‘categories’

, ‘on’, ‘c.id = p.category_id’))

, ‘where’ => “name like ‘%lemon%’ ”

, ‘order_by’ => ‘p.name’

));

$q->add_select(‘p.subname’)

$q->add_ijoin(…)

$q->set_limit(…)

$q->load($q_spec)

Customizing the SQL

$dbquery = array(

‘select’ => ‘c.name as category_name’

, ‘ijoin’ => array(‘c’ => rba::_(‘table’, ‘categories’

, ‘on’, ‘c.id = p.category_id’)))

mg(‘products’)->get(product_id, compact(‘dbquery’))

Objectives/ Scope

Business Owner’s View

Architect’s View*

Designer’s** View

Builder’s View***

Functioning System

List of Important

Things

Terms, Definitions

Entity/ Relationship

Diagram

Tables, Classes

Data, physical storage design

List of Processes

Business Process Model

Essential Functions

System Design

Detailed Program Design

Business Locations

Operationsby Business

Location

Data Links, Processing Locations

Network Architecture

(h/w, s/w types)

Network Construction

Organi- zational

Units

Org. Chart, Roles

Roles+Data

(Use Cases)

User Interface, Security

Screens, Security Design

Business Events, Cycles

Master Business Schedule

State/ transactions,

ELH

“Control Flow”

diagrams

Timing Definitions

Business Vision and Mission

Business Policies and

Rules

Business Rule Model

Rule Design

Rule Specification

Working System

Network(Where)

Data(What)

Activities(How)

People(Who)

Timing(When)

Motiva-tion (Why)

* John Z calls this the “information designer’s” perspective.

** He calls this the “builder’s” view.

*** This is John Z’s “sub-contractor’s” view.

Zachman Framework