The document discusses PHP Database Objects (PDO) and abstracting database interfaces. It provides background on the speaker, Lukas Kahwe Smith, and their experience with PHP. It then discusses reasons for abstracting database interfaces like supporting multiple database types, forward compatibility, and reducing vendor lock-in. The remainder of the document focuses on different types of abstraction layers that can be built on top of PDO including database APIs, SQL abstraction, active records, and object-relational mapping (ORM) layers. It provides examples of several popular abstraction frameworks and how they implement different levels of abstraction.

1. PDO – PHP Database Objects
Amsterdam, June 16th 2007
Dutch PHP Conference
Lukas Kahwe Smith (lsmith@optaros.com)
http://pooteeweet.org/files/dutchphpconf07/pdo_comments.pdf

2. About Myself
Lukas Kahwe Smith
Started using PHP in the late PHP3 days
Joined PEAR sometime in 2002
Began posting on internals@lists.php.net in 2003
Started the unofficial official PHP todo list in 2005
Makes his living as a consultant for Optaros
• OSS consulting and system integration firm
• We are always hiring
– http://optaros.com/en/company/careers
Can be reached
• Via Email: lsmith@optaros.com
• On IRC: “lsmith” on efnet, freenode, ircnet ..
• In Person: Here or at Ultimate Frisbee tournaments
06/16/07 © Optaros 2007. All rights reserved. 2

3. Why abstract your database interface?
Support for multiple RDBMS
Forward compatibility with new RDBMS versions
Vendor Lock in
Training costs
Pushing your own preference to the client
Higher level API
06/16/07 © Optaros 2007. All rights reserved. 3

4. And now for the meat ..
Actually Wez has so nice slides about PDO lets just use those
• http://images.omniti.net/omniti.com/talks/furlong-pdo-
long.pdf
I will add a few more slides at the end about layers build on
top of PDO
• Actually I rarely use PDO directly at all
Oh and did I mention we are also hiring?
• http://optaros.com/en/company/careers
06/16/07 © Optaros 2007. All rights reserved. 4

5. Types of abstraction layers?
Database API Abstraction
• Provide a common API
Database SQL Abstraction
• Provide a common API as well as methods to construct
portable SQL
ActiveRecord (and friends)
• Wrap around schema to provide an OO interface
• No need to write the standard day to day SQL
ORM
• Pure OO code that generates SQL
• OO code defines SQL schema implicitly
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6. Database SQL Abstraction and ORM Layers
Raw SQL
• $sql = “SELECT * FROM Person WHERE name='Smith'“;
• $all_smiths = $db->getAll($sql);
Query-By-Example
• $user = new User();
• $user->name = 'Smith';
• $all_smiths = Query::execute($user);
Query-By-API
• $q = new Query();
• $c = new EqCriteria('Name', 'Smith');
• $q->Form('Person')->Where($c);
• $all_smiths = $q->execute();
Query-By-Language
• $q = “FROM Person p WHERE p.name = 'Smith'”
• $all_smiths = $conn->query($q);
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7. Database SQL Abstraction and ORM Layers
ezc::Database
• Raw SQL
• Persistent Objects (via ezc:PersistentObject)
Zend_DB
• Raw SQL
• Table Gateway Pattern (via Zend_DB_Table)
Doctrine
• Raw SQL, Query-By-Language and Query-By-API
Propel 1.3
• Raw SQL. Query-By-API
MetaStorage
• Raw SQL. Query-By-API (XML based meta programming
language and code generator)
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8. ?
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