Call to a member function fetch() on a non-object - php

Question

I am new in php and have seen many post related to this error but still can not find the problem. I also tried with the try catch block and did not get the exception. There is no connection problem and have also tested the query in my database.
$host="mysql:host=".$host_name.";dbname=".$dbname;
$ques_code=1;
$dbh = new PDO($host, $dbuser, $dbpass);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$S=$dbh->prepare("SELECT q_code FROM question_code_submission WHERE q_num = :id");
$S->bindParam(':id', $ques_code);
$temp_name=$S->execute();
$code_name=$temp_name->fetch(PDO::FETCH_ASSOC);
$code_name=$code_name['q_code'];

Answer 1

$S->execute() returns true or false, so $temp_name is being set to a boolean value - which explains why you can't call $temp_name->fetch() - it's not an object.
You don't need $temp_name at all, simply:
$S->execute();
$code_name = $S->fetch(PDO::FETCH_ASSOC);

Answer 2

$host="mysql:host=".$host_name.";dbname=".$dbname;
$ques_code=1;
$dbh = new PDO($host, $dbuser, $dbpass);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$S=$dbh->prepare("SELECT q_code FROM question_code_submission WHERE q_num = :id");
$S->bindParam(':id', $ques_code);
$success = $S->execute();
if(!$success){
echo "Query failed !!";
}else{
$result=$S->fetch(PDO::FETCH_ASSOC);
$code_name = $result['q_code'];
echo $code_name;
}