为什么不能在review表中插入数据？

Question

The error mentions that a violation of foreign key constraints.

MY ERROR: sqlalchemy.exc.IntegrityError: (psycopg2.errors.ForeignKeyViolation) insert or update on table "reviews" violates foreign key constraint "reviews_book_id_fkey" DETAIL: Key (book_id)=(770) is not present in table "reviews".

MY QUERY:

db.execute("INSERT INTO reviews (comment, score, user_id, book_id) VALUES (:comment, :score, :user_id, :book_id)", {"comment":comment, "score": score, "user_id": user.id, "book_id": book_id})
    db.commit()

MY TABLES:

UPDATE: The books in the table "books" do exist!

In case the problem may be in the populating process, here is a piece of code on how I populated the "books" table:

f = open("books.csv") 
reader = csv.reader(f) 
for isbn, title, author, year in reader: 
   if year != 'year': 
      db.execute("INSERT INTO books (isbn, title, author, year) VALUES (:isbn, :title, :author, :year)", {"isbn": isbn, "title": title, "author": author, "year": year}) 
db.commit()

UPDATE #2: here is a snapshot of my table "books" and the ID is visible:

Answer 1

I finally did some research and solved it, it turned out I was using postgreSQL, and I am newbie. so I looked at the postgreSQL syntax and I decided to drop my review table and create it again. This first piece of code is how I CREATED my old table (the one that didn't work)

CREATE TABLE reviews(
 id SERIAL PRIMARY KEY,
 score INTEGER NOT NUL,
 comment VARCHAR NOT NULL,
 user_id INTEGER REFERENCES users, #HERE WAS THE MISTAKE 
 book_id INTEGER REFERENCES books) #AND HERE AGAIN THE MISTAKE

So as you can see I forgot to add the id column to the tables:

CREATE TABLE reviews(
 id SERIAL PRIMARY KEY,
 score INTEGER NOT NUL,
 comment VARCHAR NOT NULL,
 user_id INTEGER REFERENCES users(id),  # AND HERE I FIXED IT
 nook_id INTEGER REFERENCES books(id))  # AND HERE TOO

Simple mistake but it took me a while to figure it out. Like I said always read the docs and check if the syntax is right, my mistake here was to assume that referencinf to the table would be enough, and that would take the id as default foreign key. Never assume, lesson learned.