<?php

$_POST = [
    "ambiente" => "",
    "logotipo" => "Novo logotipo",
    "certificado" => "",
    "senha" => ""
];

$id = 1;

$data = array_filter($_POST);

$fields = array_map(function ($value, $key) {
    return sprintf("`%s`='%s'", $key, $value);
}, $data, array_keys($data));

$query = sprintf("UPDATE `tabela` SET %s WHERE `id`=%d", implode(",", $fields), $id);

echo $query, PHP_EOL;