Some PDO drivers return a larger array. For example, the SQL Server driver returns 5 values.
For example:
<?php
$numRows = $db->exec("DELETE FROM [TableName] WHERE ID between 6 and 17");
print_r($db->errorInfo());
?>
Result:
Array
(
[0] => 00000
[1] => 0
[2] => (null) [0] (severity 0) []
[3] => 0
[4] => 0
)