PDO Prepared Statement - Different behavior inside 2 similar methods - php

Question

I would like someone to explain me why the first method works only after quoting the placeholder ':cat_id' in the WHERE clause, and requires the $this->db->query($query);, otherwise it throws fatal error:
"SQLSTATE[HY093]: Invalid parameter number: number of bound variables
does not match number of tokens in..."
while the second method doesn't need neither quoting and the $this->db->query() method?
public function getAllPosts($cat_id = null)
{
// Query build
$query = "SELECT posts.*, users.username, categories.title FROM posts "
. "INNER JOIN users "
. "ON posts.user_id = users.id "
. "INNER JOIN categories "
. "ON posts.category_id = categories.id ";
// Filter
if (!is_null($cat_id))
{
$query .= "WHERE category_id = ':cat_id' ";
// Order query
$query .= "ORDER BY create_date DESC";
$this->db->bind(':cat_id', $cat_id);
}
else
{
$query .= "ORDER BY create_date DESC";
}
$this->db->query($query);
// Run the query
// Assign Result Set
$results = $this->db->resultset();
return $results;
}
public function getCategoryPosts($cat_id)
{
$query = "SELECT posts.*, users.username, categories.title FROM posts "
. "INNER JOIN users "
. "ON posts.user_id = users.id "
. "INNER JOIN categories "
. "ON posts.category_id = categories.id "
. "WHERE posts.category_id = :cat_id "
. "ORDER BY create_date DESC";
$this->db->bind(':cat_id', $cat_id);
$results = $this->db->resultset();
return $results;
}
Update:
Here are a echo output of the query from the first method:
1. with quoted:
SELECT posts.*, users.username, categories.title FROM posts
INNER JOIN users ON posts.user_id = users.id
INNER JOIN categories ON posts.category_id = categories.id
WHERE category_id = ':cat_id' ORDER BY create_date DESC
2. unquoted:
SELECT posts.*, users.username, categories.title FROM posts
INNER JOIN users ON posts.user_id = users.id
INNER JOIN categories ON posts.category_id = categories.id
WHERE category_id = :cat_id ORDER BY create_date DESC

Answer 1

You are missing a trailing space on the following string
$query .= "WHERE category_id = ':cat_id'";
So you are concatenating it into:
WHERE category_id = ':cat_id'ORDER BY create_date DESC
If you remove the ', you would get:
WHERE category_id = :cat_idORDER BY create_date DESC
So PDO expects a bound value for :cat_idORDER
Also in getCategoryPosts() you create a query but never actually use it.