Insert input value into two different tables with the same userId - php

Question

I need to send the values of username, password, mail, first name and last name into two different tables in my database. I have made that possible with this code, and i get the values correct. I have one problem tho. When the user-info goes into "users" table, it auto-generates one userId. That same userId i need to use and put into the other table "usermeta" to connect the information to the correct user. What happens now is that i get a userId in the users table, but in the usermeta table the userId is = 0 on all new users. Can anyone help me?
if (isset($_POST['username']) and isset ($_POST['password'])) {
$username = $mysqli->real_escape_string($_POST['username']);
$password = md5($mysqli->real_escape_string($_POST['password']));
$email = $mysqli->real_escape_string($_POST['mail']);
$fname = $mysqli->real_escape_string($_POST['fname']);
$lname = $mysqli->real_escape_string($_POST['lname']);
$query = <<<END
INSERT INTO users(username,pass,email,admin)
VALUES('{$username}','{$password}','{$email}','{$_POST['admin']}')
END;
$q = <<<END
INSERT INTO usermeta(first_name,last_name)
VALUES('{$fname}','{$lname}')
END;
if ($mysqli->query($query) !== TRUE) {
die("Could not query database" . $mysqli->errno . " : " . $mysqli->error);
}
if ( $mysqli->query($q) !== TRUE) {
die("Could not query database" . $mysqli->errno . " : " . $mysqli->error);
header('Location:home.php');
}
}
I got a form further down in the code that the info comes from that's going to the database, but it's the php-code that makes the error i assume to i exclude that code.
Thanks!
EDIT:
I've tried to implement your different comments. Thanks alot for the answers!
If i try to get the latest id inbetween the $query and $q, the output is 0. If i use the command:
if ($mysqli->query($query) === TRUE) {
$last_id = $mysqli->insert_id;
echo $last_id;
} else {
echo "Error: " . $query . "<br>" . $mysqli->error;
}
I get the correct id. But how can i use that variable to the new $q? It seems that the function breaks after the if is done.
Thanks! :)

Answer 1

You can use LAST_INSERT_ID() to retrieve the value of the auto-increment id that was created in your last insert. (Docs here)
So try:
$q = <<<END
INSERT INTO usermeta(first_name,last_name, userId)
VALUES('{$fname}','{$lname}', LAST_INSERT_ID();)
END;

Answer 2

Okey i managed to get it done. Thanks guys for the help!
The working code looks like this:
$query = <<<END
INSERT INTO users(username,pass,email,admin)
VALUES('{$username}','{$password}','{$email}','{$_POST['admin']}')
END;
if ($mysqli->query($query) === TRUE) {
$last_id = $mysqli->insert_id;
} else {
echo "Error: " . $query . "<br>" . $mysqli->error;
}
$q = <<<END
INSERT INTO usermeta(first_name,last_name, user_id)
VALUES('{$fname}','{$lname}','{$last_id}')
END;
if ($mysqli->query($q) !== TRUE) {
die("Could not query database" . $mysqli->errno . " : " . $mysqli->error);
}