PHP PDO query works without parameters but not with - php

Question

I have a very simple query that works when I don't use parameters. With parameters, it returns nothing. Someone else posted the same issue over here:
Query with input parameters doesn't work whereas direct query works
However no one has answered it. Below is my code.
require_once('database.class.php');
class Plan extends Database {
public function getBenefitAmounts($plan_id, $group_id, $level) {
$sql = 'SELECT DISTINCT benefit FROM rates WHERE plan_id = :plan AND group_id IS NULL AND `level` = :lvl';
$params = array(':plan'=>896, ':lvl'=>1);
$this->sqlQuery($sql, $params);
// $sql = 'SELECT DISTINCT benefit FROM rates WHERE plan_id = 896 AND group_id IS NULL AND `level` = 1';
// $this->sqlQuery($sql);
$results = $this->sth->fetchAll(PDO::FETCH_COLUMN);
$options = '';
foreach ($results as $value) {
$options .= '<option value="' . $value . '">$' . $value . '</option>';
}
return $options;
}
}
In the database class:
public function sqlQuery($sql, $values_to_bind=null) {
$this->sth = $this->pdo->prepare($sql);
if (isset($values_to_bind)) {
foreach ($values_to_bind as $param => $value) {
$this->sth->bindValue($param, $value);
}
}
$success = $this->sth->execute();
if (!$success) {
$arr = $this->$sth->errorInfo();
print_r($arr);
}
}
The code commented out of the first code snippet works just fine, but with parameters, it returns nothing. The getBenefitAmounts function is called from another PHP file which is called using a JQuery get.

Answer 1

Did you try to add the third param which is optional for bindValue(). It can be something like PDO::PARAM_INT, PDO::PARAM_STR etc. Just try to debug and see if it helps.

Answer 2

I don't know why do you like so much try...catch if you use with no sense code. Because this technique: } catch (PDOException $e) { throw new PDOException($e);} means the same as } catch (PDOException $e) {;} like you ask php to do nothing if catch. Why do you asked to catch if you do nothing in case it happens?
Now my guess about how to fix your code:
public function sqlQuery($sql, $values_to_bind=null) {
$this->sth = $this->pdo->prepare($sql);
if (isset($values_to_bind)) {
foreach ($values_to_bind as $param => $value) {
$this->sth->bindValue($param, $value);
}
}
$success = $this->sth->execute();
if (!$success) {
$arr = $this->$sth->errorInfo();
print_r($arr);
}
}
By the way you use $this->sth = $this->pdo->prepare($sql); that means your sqlQuery function is a method of some class that you didn't show to us. and your first piece of code is somewhere outside that class? it would be better if you post full version of code, not just lines you think are involved.
and here you can switch to regular way:
//$results = $this->sth->fetchAll(PDO::FETCH_COLUMN); //you don't need it
$options = '';
while ($row = $this->sth->fetch(PDO::FETCH_ASSOC)) {
$options .= '<option value="' . $row['benefit'] . '">$' . $row['benefit'] . '</option>';
}

Answer 3

Why not bind the parameters using bindParam?
$plan = 896;
$lvl = 1;
$sth = $dbh->prepare("SELECT DISTINCT benefit FROM rates WHERE plan_id = :plan AND group_id IS NULL AND `level` = :lvl");
$sth->bindParam(":plan", $plan);
$sth->bindParam(":lvl", $lvl);
$sth->execute();
$r = $sth->fetchAll();