text: create table message (	id bigint generated by default as identity,	receiver_id bigint null,	message varchar(256),	receive_date timestamp,	primary key (id))
  create table account (	id bigint generated by default as identity,	name varchar(64) not null,	email varchar(128),	hash_password varchar(255),	primary key (id))
  create table book (	id bigint generated by default as identity,	douban_id varchar(64) not null,	title varchar(128) not null,	url varchar(255),	description varchar(255),	owner_id bigint not null,	onboard_date timestamp,	status varchar(32) not null,	borrower_id bigint null,	borrow_date timestamp, primary key (id))
  