Insert date in mysql using php mysqli functions - php

Question

I have this REST api code on backend:
public function createDay($user_id, $day, $startLocation, $startTime) {
$stmt = $this->conn->prepare("INSERT INTO days(day,startLocation,startTime,dayDate) VALUES(?,?,?,?)");
$stmt->bind_param("ssss", $day, $startLocation, $startTime, $dayDate);
$result = $stmt->execute();
$stmt->close();
if ($result) {
// task row created
// now assign the task to user
$new_day_id = $this->conn->insert_id;
$res = $this->createUserDay($user_id, $new_day_id, $dayDate);
if ($res) {
// task created successfully
return $new_day_id;
} else {
// task failed to create
return NULL;
}
} else {
// task failed to create
return NULL;
}
}
and function createDay:
public function createUserDay($user_id, $day_id, $dayDate) {
$stmt = $this->conn->prepare("INSERT INTO user_days(user_id, day_id, $dayDate) values(?, ?, ?)");
$stmt->bind_param("iis", $user_id, $day_id, $dayDate);
$result = $stmt->execute();
if (false === $result) {
die('execute() failed: ' . htmlspecialchars($stmt->error));
}
$stmt->close();
return $result;
}
}
this is dbhandler file, now i have a question -
I use
$new_day_id = $this->conn->insert_id;
to get ID of current data but also how I can get $dayDate to use into createUserDay function
So I need to get $dayDate and use it into createUserDay function, is there any way?