PDO query returning empty

Question

I have a Connection class file which allows my other class "Functions" to connect to my MySQL database. However, when I execute a MySQL query, it returns with just Array () . The data I'm selecting is, in fact, there (I checked). What could the problem be?

Connection.php

 <?php

 class Connection extends PDO {

 private $username;
 private $password;
 private $database;
 private $hostname;

 public function __construct($hostname, $username, $password, $database) {

    $this->hostname = $hostname;
    $this->username = $username;
    $this->password = $password;
    $this->hostname = $hostname;

    try {
        parent::__construct("mysql:host=" . $this->hostname . ";dbname=" . $this->database, $this->username, $this->password);
    }

    catch (PDOException $e) {
        echo $e->getMessage();
    }
  }
}

?>

Functions.php

<?php

require_once "Connection.php";

class Functions {

private $connection;

public function __construct() {
    $this->connection = new Connection("127.0.0.1", "xxx", "xxx", "xxx");
}

public function sqlFetchAssoc($query) {

    $sth = $this->connection->prepare($query);
    $sth->execute();
    $result = $sth->fetchAll(PDO::FETCH_ASSOC);

    return $result;
    }
}

$functions = new Functions();
$row = $functions->sqlFetchAssoc("SELECT * FROM chatlogs WHERE id = 70");

print_r($row);

?>

Answer 1

I just spotted your bug in Connection.php :

$this->hostname = $hostname;
$this->username = $username;
$this->password = $password;
$this->hostname = $hostname;

$this->hostname is repeated while $this->database is not set . However, you can strip altogether setting the $this->something , since you are using those values in the same function. This will make it simpler:

try {
    parent::__construct("mysql:host=" . $hostname . ";dbname=" . $database, $username, $password);
}

I'd recommend going a step further. You should test each class separately. You can write this script and debug it (if needed) in testfunction.php :

<?php
class Functions {
private $connection;

public function __construct() {
    $this->connection = new PDO("mysql:host=127.0.0.1;dbname=xxx", "xxx", "xxx");
}

public function sqlFetchAssoc($query) {

    $sth = $this->connection->prepare($query);
    $sth->execute();
    $result = $sth->fetchAll(PDO::FETCH_ASSOC);

    return $result;
    }
}

echo "Test started <br><br>";
echo "Initialization: <br>";
$functions = new Functions();
echo "Correct<br><br>";
echo "Performing a select: <br>";
$row = $functions->sqlFetchAssoc("SELECT * FROM chatlogs WHERE id = 70");
print_r($row);
echo "Test finished.";
?>

Then do something similar for the first class. Then not only it will be easier to spot the bug, but should a bug happen, you can come to these tests to see what went wrong instead of writing them all again. Remember not to include them in production code.