Key Validation for DB design

sql_schema.sql

CREATE TABLE book (
  title varchar(100),
  isbn varchar(50) PRIMARY KEY,
  pages integer,
  price money,
  description varchar(256),
  publisher varchar(100)
);

CREATE TABLE chapter (
  id integer PRIMARY KEY,
  number integer,
  title varchar(50),
  content varchar(1024)
);

CREATE TABLE author (
  name varchar(50),
  bio varchar(100),
  email varchar(20) PRIMARY KEY
);

  SELECT 
    constraint_name, table_name, column_name
  FROM
    information_schema.key_column_usage
  WHERE
    table_name = 'book';

 SELECT 
    constraint_name, table_name, column_name
  FROM
    information_schema.key_column_usage
  WHERE
    table_name = 'chapter';


 SELECT 
    constraint_name, table_name, column_name
  FROM
    information_schema.key_column_usage
  WHERE
    table_name = 'author';