Description:
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pdo mysql error.
PDO::FETCH_ORI_REL not working

sql result about 1000 rows.
I need to catch 555. row item but i get always first row (0.) of result.


Reproduce code:
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$this->db_conn = new PDO("mysql:host=$db;dbname=mysql;EnableScrollableCursors=1",$db_username,$db_password);//connect mysql
$sql = "select * from tablename";
$this->db_conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT);
//$stmt = $this->db_conn->query($sql) or die("ERROR: " . implode(":", $this->db_conn->errorInfo()));
$stmt = $this->db_conn->prepare($sql,  array( PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL )	);
$stmt->execute();
$search_row = 555;
$row = $stmt->fetch(PDO::FETCH_NUM , PDO::FETCH_ORI_REL, $search_row );
var_dump($row);

Expected result:
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catch 555. row

Actual result:
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catch first row