Get Last Executed Query in PHP PDO

<?php

class MyPDOStatement extends PDOStatement
{
  protected $_debugValues = null;

  protected function __construct()
  {
    // need this empty construct()!
  }

  public function execute($values=array())
  {
    $this->_debugValues = $values;
    try {
      $t = parent::execute($values);
      // maybe do some logging here?
    } catch (PDOException $e) {
      // maybe do some logging here?
      throw $e;
    }

    return $t;
  }

  public function _debugQuery($replaced=true)
  {
    $q = $this->queryString;

    if (!$replaced) {
      return $q;
    }

    return preg_replace_callback('/:([0-9a-z_]+)/i', array($this, '_debugReplace'), $q);
  }

  protected function _debugReplace($m)
  {
    $v = $this->_debugValues[$m[1]];
    if ($v === null) {
      return "NULL";
    }
    if (!is_numeric($v)) {
      $v = str_replace("'", "''", $v);
    }

    return "'". $v ."'";
  }
}

// have a look at http://www.php.net/manual/en/pdo.constants.php
$options = array(
  PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
  PDO::ATTR_STATEMENT_CLASS => array('MyPDOStatement', array()),
);

// create PDO with custom PDOStatement class
$pdo = new PDO($dsn, $username, $password, $options);

// prepare a query
$query = $pdo->prepare("INSERT INTO mytable (column1, column2, column3)
  VALUES (:col1, :col2, :col3)");

// execute the prepared statement
$query->execute(array(
  'col1' => "hello world",
  'col2' => 47.11,
  'col3' => null,
));

// output the query and the query with values inserted
var_dump( $query->queryString, $query->_debugQuery() );

Most people create a wrapper class around the PDO object to record the queries as they are sent to the database. Hardly anyone uses a direct PDO object since you can add extra helper methods by wrapping, or extending PDO.

/**
 * Run a SQL query and return the statement object
 *
 * @param string $sql query to run
 * @param array $params the prepared query params
 * @return PDOStatement
 */
public function query($sql, array $params = NULL)
{
    $statement = $this->pdo->prepare($sql);

    $statement->execute($params);

    // Save query results by database type
    self::$queries[] = $sql;

    return $statement;
}