PHP/MYSQL: showing data out of 2 tables - php

Question

This is my first question and I tried to make it clear enough so you guys/girls can understand it. If I am missing something or doing something wrong please let me know! Its my first question.
What I want:
I want it to show the voornaam out of the table Klanten to show next to the other ones out of the table onderwerpen. For example I want the voornaam to show next to the henk and koken. So I expect it to show the data out 2 different tablesin the block you can see on the pic.
I tried using a foreach loop with 2 conditions but that it not possible. So I was wondering what the solution in this case needs to be. Because It works with 1 condition in the foreach but it is not possible to do this with 2 conditions.
What I have tried:
<div class="box box-primary">
<div class="box-header with-border">
<h3 class="box-title">Onderwerpen</h3>
</div><!-- /.box-header -->
<div class="box-body">
<?php
$onderrwerp = $app->get_onderwerpen();
$klantten = $app->get_klanten();
foreach($onderrwerp as $onderwerp and $klantten as $klant){
echo '<div class="well well-sm">';
echo '' . $onderwerp['voornaam'].'';
echo '<h3>'.$onderwerp['naam'].'</h3><br>';
echo '' .$onderwerp['naam'].'';
echo '</div>';
}
?>
The code:
<div class="box box-primary">
<div class="box-header with-border">
<h3 class="box-title">Onderwerpen</h3>
</div><!-- /.box-header -->
<div class="box-body">
<?php
$onderrwerp = $app->get_onderwerpen();
foreach($onderrwerp as $onderwerp){
echo '<div class="well well-sm">';
echo '<h3>'.$onderwerp['naam'].'</h3><br>';
echo '' .$onderwerp['naam'].'';
echo '</div>';
}
?>
The functions:
public function get_onderwerpen(){
$getOnderwerp = $this->database->query("SELECT * FROM onderwerpen ORDER BY id ASC");
$onderwerpen = $this->database->resultset();
return $onderwerpen;
}
public function get_klanten(){
$getKlant = $this->database->query("SELECT * FROM klanten ORDER BY punten DESC");
$klanten = $this->database->resultset();
return $klanten;
}

Answer 1

So you have two tables. they are connected using the ledenpagina_id field I assume looking at your data.
What you are looking for is to JOIN the two tables so that with one query you can fetch the data you want and then do a loop to show the data:
SELECT *
FROM klanten JOIN onderwerpen
ON klanten.lendenpagina_id = onderwerpen.lendenpagina_id
You can then add WHERE clause, ORDER_BY and so on.