You have a typos here:
$stmt->bind_param(
"sisssssssssssssssssssssssssii",
$record["code"],
$record["pairCode"],
.....
$record["variant:Dětská velikost"], // here is a mistake in the key. It should be "variant:Dětská Velikost"
$record["variant:Množství"]
);
if (!$stmt->execute()) {
echo "Error: " . $stmt->error . "<br>";
}
I reproduced your code as I could, corrected typos in the key and it works for me now. If it doesn't for you, please provide the full code.
Hope it helps. Cheers.
p.s. If you dump the $record var after binding it will be:
array(2) {
["variant:Dětská Velikost"]=>
string(30) "variant:Dětská velikost"
["variant:Dětská velikost"]=> // here is a broken / mistaken key after binding with null value
&NULL
}