Passing variable to mysql query results in "function query on null" - php

Question

I have a class that I am passing a query to, but the fatal error
function query on null'
occurs when attempting to run the query.
I echoed $mysql_statement and got
select * from users
which is the intended query, but in the context of the query statement it keeps telling returning the fatal error function query on null.
Any ideas on why the "select * from users" that is legitimately stored in $mysql_statement is being interpreted as null? (the properties used and not defined here are defined in a parent class):
The page.php:
<?php
include("includes/database_classes.php");
new database_connection;
new database_query("SELECT * FROM users");
?>
...and the database_classes.php:
<?php
/*----------------------------------------------------------------------------------------------------*/
class database_connection
{
protected $username = 'root';
protected $password = '';
protected $hostname = 'localhost';
protected $database = 'assistant';
protected $database_handle;
function connect()
{
try
{
$database_handle = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);
}
catch (PDOException $e)
{
print "Error!: " . $e ->getMessage() . "<br/>";
die();
}
}
}
/*----------------------------------------------------------------------------------------------------*/
class database_disconnection extends database_connection
{
function disconnect()
{
$database_handle = null;
}
}
/*----------------------------------------------------------------------------------------------------*/
class database_query extends database_connection
{
protected $mysql_statement;
function __construct( $mysql_statement )
{
$this->mysql_statement = $mysql_statement;
echo $mysql_statement;
foreach($this->database_handle->query("$mysql_statement")->fetch_assoc() as $row) {
print_r($row);
}
}
}
/*----------------------------------------------------------------------------------------------------*/

Answer 1

I think you are having problem when trying to loop through the result of your SQL query, this happened because, you didn't include method "fetch_assoc()"
Instead of:
foreach($this->database_handle->query("$mysql_statement") as $row);
Why not?
foreach($this->database_handle->query("$mysql_statement")->fetch_assoc() as $row)