It's working like that:
$servername = "localhost";
$username = "xxx";
$password = "xxx";
$dbname = "energy";
date_default_timezone_set("Europe/Sofia");
$h = date('H');
$m = date('i');
$month = date('n');
//$year = date('Y');
$conn = mysqli_connect($dbservername, $dbusername, $dbpassword, $dbname);
$api_key_value = "tPmAT5Ab3j7F9";
$api_key = $voltage = $current = $frequency = $power = $energy = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$api_key = ($_POST["api_key"]);
if($api_key == $api_key_value) {
$voltage = ($_POST["voltage"]);
$current = ($_POST["current"]);
$frequency = ($_POST["frequency"]);
$power = ($_POST["power"]);
$energy = ($_POST["energy"]);
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
switch($month) {
case 12:{
if (($h >= 06 && $m >=00 ) && ($h <= 21 && $m <=59)) {
$sql = "INSERT INTO energy_home_January (voltage,current,frequency,power,energy)
VALUES ('" . $voltage . "', '" . $current . "', '" . $frequency . "', '" . $power . "', '" . $energy . "')";
}
else{
$sql = "INSERT INTO energy_home_January_night (voltage,current,frequency,power,energy)
VALUES ('" . $voltage . "', '" . $current . "', '" . $frequency . "', '" . $power . "', '" . $energy . "')";
}
}
break;