I can't use a nested loop as foreach - php

Question

The problem is easy. The answer is not
I have an array with multiple (2) dimensions.
The code is easy (line 28-32):
<?php
foreach($select_all_data as $key => $value) {
foreach ($value as $v => $k) {
$all_values = $v.",";
}
}
?>
But when I excecute it, it shows me
Warning: Invalid argument supplied for foreach() in D:\xampp\htdocs\qlb\test.php on line 29
(I also tested $value al array with is_array, that gave me true)
An example output of $value in the loop is:
array(12) {
["id"]=>
string(3) "101"
["aangever_voornaam"]=>
string(8) "censored"
["aangever_achternaam"]=>
string(6) "censored"
["aangever_geslacht"]=>
string(3) "Male"
["pleegplaats"]=>
string(6) "censored"
["pleegdatum"]=>
string(10) "dd-mm-yyyy"
["pleegtijd"]=>
string(5) "hh:mm"
["verbalisant"]=>
string(12) "censored"
["verklaring"]=>
string(229) "censored"
["opnamedatum"]=>
string(19) "yyyy-mm-dd hh:mm:ss"
["status"]=>
string(4) "open"
["behandelaar"]=>
string(12) "censored"
}
As you can see, its a nice array that I want to put in the loop. But it gives me the invalid argument error.
What did I do wrong?
For the record: I tried to create a script to export a whole database with this script
<?php
$DB_HOST = "";
$DB_USER = "";
$DB_PASS = "";
$DB_NAME = "";
$con = new mysqli($DB_HOST, $DB_USER, $DB_PASS, $DB_NAME);
if($con->connect_errno > 0) {
die('Connection failed [' . $con->connect_error . ']');
}
$select_all_tables = array();
$select_all_data = array();
$show_tables_from = $con->query("SHOW TABLES FROM `$DB_NAME`");
while ($row = $show_tables_from->fetch_assoc()) {
$select_all_tables[] = $row['Tables_in_'.$DB_NAME.''];
}
foreach ($select_all_tables as $a) {
$q = $con->query("SHOW CREATE TABLE `$a`");
$show_create_table[] = $q->fetch_assoc()['Create Table'];
$q = $con->query("SELECT * FROM `$a`");
$select_all_data[] = $q->fetch_assoc();
}
echo "<pre>";
//var_dump($a);
//var_dump($show_create_table);
//var_dump($select_all_data);
foreach($select_all_data as $key => $value) {
var_dump($value);
}
?>

Answer 1

Acording to fetch_assoc docs
Returns an associative array that corresponds to the fetched row or
NULL if there are no more rows.
So for those $value elements inside the loop that end up being null you will have that error thrown..
So just wrap it in if statement like:
if (!is_null($value)) {
foreach ($value as $v => $k) {
$all_values = $v.",";
}
}
or maybe even is_array($value) to make sure you able to iterate thru...

Answer 2

The arrays had a diffrent number of keys. I think because I forgot to loop the query in the first foreach (after the while)
So I changed that to
foreach ($select_all_tables as $a) {
$q = $con->query("SHOW CREATE TABLE `$a`");
$show_create_table[] = $q->fetch_assoc()['Create Table'];
$q = $con->query("SELECT * FROM `$a`");
while ($row = $q->fetch_assoc()) {
$select_all_data[] = $row;
}
}
And that was the solution!