Insert into a table and a junction table with SQL

Question

I have three tables in my database and want to insert some data, but I can't seem to make it work.

Database structure (mysql & InnoDB)

book

book_id (AI & Primary Key)
book_original_name

writer

writer_id (AI & Primary Key)
writer_name

book_who_wrote_it

book_id (Foreign Key from book table)
writer_id (Foreign Key from writer table)

What I am trying to do is:

1-) Insert a new book into book table.

2-) Insert data into junction table. (contains book_id and writer_id)

3-) I don't want to add new writers and want to add existing writers into my junction table, my writer table contains all writers I want.

And here's what I've tried so far. ($sqli is my connection variable)

$add_book_original_name = htmlspecialchars($_POST['book_original_name']);
$add_book_original_name = mysqli_real_escape_string($sqli, $add_book_original_name);

$stmt = $sqli->prepare("INSERT INTO book(book_original_name) VALUES (?)");
$stmt->bind_param("s", $add_book_original_name);
$stmt->execute();
$stmt->close();

    // junction table stuff

    $get_book_id = $sqli->insert_id; // I am trying to get the last inserted book id
    $get_writer_id = $sqli->prepare("SELECT writer_id FROM writer WHERE writer_name = $add_book_writer_name ");
    $stmt->bind_param("i", $get_writer_id);
    $stmt->execute();
    $stmt->close();

    $stmt = $sqli->prepare("INSERT INTO book_who_wrote_it(book_id, writer_id) VALUES($get_book_id, $get_writer_id)");
    $stmt->bind_param("ii", $get_book_id, $get_writer_id);
    $stmt->execute();
    $stmt->close();