how use mysql_data_seek with PDO? - mysql

Question

I want use mysql_data_seek with PDO from google search I found that it should looks like this:
$row0 = $result->fetch(PDO::FETCH_ASSOC, PDO::FETCH_ORI_ABS, 0);
however it's not work, what I do wrong?
this is my code:
$query = "SELECT name,age FROM users";
$q = $db->prepare($query);
$q->execute();
$q->setFetchMode(PDO::FETCH_ASSOC);
$arrayData = $q->fetchAll();
foreach ($arrayData as $row){
echo $row['name'] ." ";
echo $row['age'] ."<br>";
}
$result = $q->fetch(PDO::FETCH_OBJ,PDO::FETCH_ORI_ABS,4);
var_dump($result);
I just want get the 5th row in object form from the last run query. I don't want run this query again (as some guys told me) I just want the results from sql buffer.
the var_dump result is: bool(false)
any ideas?
EDIT:
thanks for your answers and sorry but maybe I don't explain myself as well. I like the trick with JSON but the point is that the 5th row is example. I just want use the result of the query from the buffer with PDO exactly as I did it with mysql_data_seek in regular mysql (change the cursor). is it possible? I like all the tricks but that not what I look for.

Answer 1

the PDO 'cursor' default is PDO::CURSOR_FWDONLY that means that cursor can't back to zero like it happens with mysql_data_seek to allow cursor back to zero it necessary define use 'scrollable cursor'
example:
$db->prepare($query, array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
before use it like this:
$row0 = $result->fetch(PDO::FETCH_ASSOC, PDO::FETCH_ORI_ABS, 0);

Answer 2

$result = $arrayData[4];
is all you need.

Answer 3

If you want the 5th row result you can do like this:
$result = json_decode(json_encode($arrayData[4]), FALSE);
var_dump($result);
or something like this:
$object = new stdClass();
foreach ($array as $key => $value)
{
$object->$key = $value;
}
Just curious! why do you need the object form?
EDIT (this will give the object form of the 5th row):
$index = 0;
$fifthRow = new stdClass();
while($row = $q->fetch())
{
if($index++==4)
$fifthRow = json_decode(json_encode($row), FALSE);
}

Answer 4

You could do it like this:
$c = 1;
$saved=null;
while($row = $q->fetch()){
if($c==4){
$saved = clone $row;
};
$c++;
somethingelse;
}
$saved will then contain the 4th element as an object with almost no extra overhead calculations.