"select *,substr(text,1,(CHAR_LENGTH(text)*0.5)) as text FROM stories"

$data=$sql->fetchAll(PDO::FETCH_ASSOC);
$length=count($data);
for($i=0;$i<$length;$i++){
    $data[$i]['text']=substr($data[$i]['text'],0,strlen($data[$i]['text'])*0.5);}