Description:
------------
While using not emulated prepared statement against MySQL 5.5, warnings (using ERRMODE_WARNING) are more verbose than errorInfo(). With prepared queries, errorInfo return (string, NULL, NULL).

This fact is true with or without ERRMODE_WARNING.

And this fact is also true, but different while using standard queries :

What the warning give me :
{{{
[WARNING] PDO::query() [<a href='pdo.query'>pdo.query</a>]: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '83-27
7727' for key 'UNIQUE'
}}}

What I got from errorInfo()[2] (Missing the "Integrity constraint violation:" string, built client side from error code ?) :
{{{
Duplicate entry '83-277727' for key 'UNIQUE'
}}}



Test script:
---------------
<?php

class My_PDOStatement extends PDOStatement
{
    public function execute($input_parameters = NULL)
    {
        $res = parent::execute($input_parameters);
        if ($res === FALSE)
            var_dump($this->errorInfo());
        return $res;
    }
}

$options = array(PDO::ATTR_PERSISTENT => FALSE,
                 PDO::ATTR_ERRMODE => PDO::ERRMODE_WARNING,
                 PDO::ATTR_EMULATE_PREPARES => FALSE,
                 PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                 PDO::ATTR_STATEMENT_CLASS => array('My_PDOStatement'));

$pdo = new PDO(...);

$stmt = $pdo->prepare("SELECT :a + :a");
$stmt->execute(array('a' => 1)); // Willingly generate 'Invalid parameter number'
var_dump($stmt->fetchAll());


Expected result:
----------------
I Expect errorInfo() to return error messages.

Actual result:
--------------
errorInfo() in this specific case return (string, NULL, NULL).