How to make mysql trigger to access another table's entry?

Question

Say there is a DB with 3 tables

1. Books table - contain book_id and its title
2. Inventory - A list of book_ids in the inventory
3. Logs - A list of log strings.

Every time I add a new book_id to the inventory, I want the title of the book to be inserted in the logs table with a trigger. Here is the code, that'll insert the book_id to the logs. How to modify this to make the trigger add the title of the book in the logs instead of its id?

CREATE TABLE book (
  book_id INT AUTO_INCREMENT PRIMARY KEY,
  title   VARCHAR(32)
);

CREATE TABLE inventory (
  book_id INT,
  FOREIGN KEY (book_id) REFERENCES book(book_id)
);

CREATE TABLE logs ( log_message VARCHAR(64) );

CREATE TRIGGER book_added
AFTER INSERT ON inventory FOR EACH ROW
INSERT INTO logs values(new.book_id);

Note: I'm new to SQL and these tables are altered and simplified so ignore the bad design.

Answer 1

How to modify this to make the trigger add the title of the book in the logs instead of its id?

You select what you need from the appropriate table:

INSERT INTO logs SELECT title FROM book where book_id = new.book_id;