PDOStatement::getColumnMeta

This method is supported in the MySQL 5.0+ driver. It can be used for object hydration:
<?php
$pdo_stmt = $dbh->execute('SELECT discussion.id, discussion.text, comment.id, comment.text FROM discussions LEFT JOIN comments ON comment.discussion_id = discussion.id');
foreach(range(0, $pdo_stmt->columnCount() - 1) as $column_index)
{
 $meta[] = $pdo_stmt->getColumnMeta($column_index);
}
while($row = $pdo_stmt->fetch(PDO::FETCH_NUM))
{
 foreach($row as $column_index => $column_value)
 {
 //do something with the data, using the ids to establish the discussion.has_many(comments) relationship.
 }
}
?>

If you are building an ORM, this method is very useful to support more natural SQL syntax. Most ORMs require the column names to be aliases so that they can be parsed and turned into objects that properly represent has_one, has_many, many_to_many relationships.

I found a short discussion related to this function at 
http://www.sitepoint.com/forums/showthread.php?t=497257
I haven't tried it (yet?) but hopefully someone can find it useful.

native_type has the following mapping for MySQL:
(tested in PHP 5.4, MySQL 5.7)
INT(11) (PKs) => LONG
TINYINT(4) => TINY
DOUBLE => DOUBLE
VARCHAR => VAR_STRING
CHAR => STRING
DATE => DATE
Functions => VAR_STRING
- DATEFORMAT()
- CONCAT()

Searching for LONGLONG in php-src: 
 
$datatypes = array(
 MYSQLI_TYPE_TINY => "TINY",
 MYSQLI_TYPE_SHORT => "SHORT",
 MYSQLI_TYPE_LONG => "LONG",
 MYSQLI_TYPE_FLOAT => "FLOAT",
 MYSQLI_TYPE_DOUBLE => "DOUBLE",
 MYSQLI_TYPE_TIMESTAMP => "TIMESTAMP",
 MYSQLI_TYPE_LONGLONG => "LONGLONG",
 MYSQLI_TYPE_INT24 => "INT24",
 MYSQLI_TYPE_DATE => "DATE",
 MYSQLI_TYPE_TIME => "TIME",
 MYSQLI_TYPE_DATETIME => "DATETIME",
 MYSQLI_TYPE_YEAR => "YEAR",
 MYSQLI_TYPE_ENUM => "ENUM",
 MYSQLI_TYPE_SET => "SET",
 MYSQLI_TYPE_TINY_BLOB => "TINYBLOB",
 MYSQLI_TYPE_MEDIUM_BLOB => "MEDIUMBLOB",
 MYSQLI_TYPE_LONG_BLOB => "LONGBLOB",
 MYSQLI_TYPE_BLOB => "BLOB",
 MYSQLI_TYPE_VAR_STRING => "VAR_STRING",
 MYSQLI_TYPE_STRING => "STRING",
 MYSQLI_TYPE_NULL => "NULL",
 MYSQLI_TYPE_NEWDATE => "NEWDATE",
 MYSQLI_TYPE_INTERVAL => "INTERVAL",
 MYSQLI_TYPE_GEOMETRY => "GEOMETRY",
 );

This method is supported by sql server too (at least the version of the PDO driver 5.7.1)
Example:
array(8) {
 ["flags"]=>
 int(0)
 ["sqlsrv:decl_type"]=>
 string(12) "int identity"
 ["native_type"]=>
 string(6) "string"
 ["table"]=>
 string(0) ""
 ["pdo_type"]=>
 int(2)
 ["name"]=>
 string(8) "IdCompra"
 ["len"]=>
 int(10)
 ["precision"]=>
 int(0)
}

I recently added a note to a small function that went through the results of PDOStatement::fetch and mapped columns to integer or float types.
I forgot to test for columns that can have a null value!
I'm updating the code here, sorry.
This website doesn't let me edit the original comment, so I'm just gonna link to a gist in case it needs even further fixes.
https://gist.github.com/AeonFr/db3b2a8a95753076d9e4da42d29365d2
I basically added this code:
<?php
if ($value === null) {
 continue;
}
?>