PHP Data Objects

The PHP Data Objects (PDO) extension defines a lightweight, consistent interface for accessing databases in PHP. Each database driver that implements the PDO interface can expose database-specific features as regular extension functions. Note that you cannot perform any database functions using the PDO extension by itself; you must use a database-specific PDO driver to access a database server

PDO has (among others) these unique features:

  • PDO is a native C extension.
  • PDO takes advantage of the latest PHP 5 internals.
  • PDO uses buffered reading of data from the result set.
  • PDO gives common DB features as a base
  • PDO is still able to access DB-specific functions
  • PDO can use transaction-based techniques
  • PDO can interact with LOBS (Large Objects) in the database
  • PDO can use prepared and executable SQL statements with bound parameters.
  • PDO can implement scrollable cursors
  • PDO has access to SQLSTATE error codes and has very flexible error handling

Making a connection using PDO

$db = new PDO ($dsn, $username, $password);

$db = new PDO(“mysql:host=localhost;dbname=library”, “petermac”, “abc123”);

Interaction with the database

$db->query(“UPDATE books SET authorid=4 WHERE pub_year=1982”);

PDO and prepared statements

PDO also allows for what are known as prepared statements. This is done with PDO calls in stages or steps. Consider the following code:

$statement = $db->prepare( "SELECT * FROM books");
// gets rows one at a time
while ($row = $statement->fetch()) {
 // or do something more meaningful with each returned row
$statement = null;

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