Create SQL code draft1

[xiaoxian920103]

CREATE TABLE User
(
name VARCHAR(256) NOT NULL,
email VARCHAR(256) NOT NULL UNIQUE PRIMARY KEY,
phoneNumber VARCHAR(256) NOT NULL UNIQUE,
major VARCHAR(256)
CONSTRAINT email CHECK(email = '%@duke.edu' OR email = '%@duke.%.edu')
);

CREATE TABLE Bid
(
date_time TIMESTAMP NOT NULL,
bid_price SMALLMONEY NOT NULL,
CONSTRAINT bid_price CHECK(bid_price >= 0)
bid_user_email VARCHAR(256) NOT NULL
REFERENCES User(email),
bid_ISBN VARCHAR(256) NOT NULL
REFERENCES Book(ISBN),
bid_seller_email VARCHAR(256) NOT NULL
REFERENCES Book(seller_email),
bid_post_time TIMESTAMP NOT NULL
REFERENCES Book(post_time),
PRIMARY KEY (bid_user_email, date_time, bid_ISBN, bid_seller_email, bid_post_time)
);

CREATE TABLE Book
(
title VARCHAR(256) NOT NULL,
ISBN VARCHAR(256) NOT NULL,
description VARCHAR(256),
condition VARCHAR(256) NOT NULL,
professor VARCHAR(256),
price SMALLMONEY NOT NULL,
course VARCHAR(256),
edition INTEGER NOT NULL,
is_auction BOOLEAN,
is_buy_it_now BOOLEAN,
start_price SMALLMONEY,
buy_it_now_price SMALLMONEY,
display boolean,
seller_email VARCHAR(256) NOT NULL
REFERENCES User(email),
post_time TIMESTAMP NOT NULL,
PRIMARY KEY(ISBN, seller_email, post_time),
CONSTRAINT condition CHECK(condition in ('new','like-new','used and good','used and poor'),
CONSTRAINT start_price CHECK((is_auction = true AND start_price >=0) OR (is_auction = false AND start_price IS NULL)),
CONSTRAINT buy_it_now_price CHECK((is_buy_it_now = true AND buy_it_now_price >= 0) OR (is_buy_it_now = false AND buy_it_now_price IS NULL))
);

CREATE FUNCTION non_auction_no_more_than_three_days() RETURNS TRIGGER AS $$
BEGIN
IF EXISTS(SELECT * FROM Book WHERE age(clock_timestamp, post_time) > 3 days AND display = true AND is_auction = false) THEN
UPDATE Book
SET display = false;
--then send the seller an nofitication email, now I don't know how to do it
END IF;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER non_auction_no_more_than_three_days
BEFORE INSERT OR UPDATE ON Book
FOR EACH STATEMENT
EXECUTE PROCEDURE no_more_than_three_days();

CREATE FUNCTION current_bid_is_valid() RETURNS TRIGGER AS $$
BEGIN
IF EXISTS(SELECT * FROM Bid WHERE new.bid_ISBN=Books.ISBN AND new.bid_seller_email=Books.seller_email AND new.bid_post_time = Books.post_time AND old.bid_price >= new.bid_price) THEN
RAISE EXCEPTION 'Must Place a Bid with Price Higher Than the Current Bid';
END IF;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER current_bid_is_valid
BEFORE INSERT OR UPDATE ON Bid
FOR EACH ROW
EXECUTE PROCEDURE current_bid_is_valid();

CREATE FUNCTION bidding_start() RETURNS TRIGGER AS $$
BEGIN
IF (SELECT bid_price FROM Bid WHERE new.bid_ISBN=Books.ISBN AND new.bid_seller_email=Books.seller_email AND new.bid_post_time = Books.post_time) IS NOT NULL THEN
UPDATE Book
SET is_buy_it_now = false,
buy_it_now_price = NULL;
END IF;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER bidding_start
BEFORE INSERT OR UPDATE ON Bid
FOR EACH STATEMENT
EXECUTE PROCEDURE bidding_start();

-- Note:
-- 1. some books might be copies of official edition books, so ISBN can no longer be part of a key.
-- 2. I added one more attribute "display" to book. When display = true, then that record remains visible on the website. When display = false, we still have this record in the database, but people can't see it on the website. When a book has passed the three-day window period, we turn display to false. When this seller wants to renew it, we turn display back to true.
-- 3. I'm not sure whether "age(clock_timestamp, post_time) > 3 days" is a valid argument or not.
-- 4. I'm not sure whether sql will fire the trigger every second (that's not a good idea). I don't know how to handle the trigger's timing part.
-- 5. A single user can only place one bid at one time.
-- 6. When is_auction is true, a start_price is required to be valid (non-negative).
-- 7. When is_buy_it_now is true, a buy_it_now_price is required to be valid (non-negative).
-- 8. To place a bid, the input bidding price must be higher than the current bidding price.
-- 9. Once bidding process starts, the buy_it_now loses its function.

-- Some initial sample data to play with.
INSERT INTO User VALUES("John Cao", "john.cao@duke.edu", "970-820-3309", "Economics and Statistics");
INSERT INTO User VALUES("Bill Wang", "bill.wang@duke.edu", "970-820-3306", "Finance");
INSERT INTO User VALUES("Iris Liu", "iris.liu@duke.edu", "970-820-2927", "Economics");
INSERT INTO User VALUES("Evelyn Wu", "evelyn.wu@duke.edu", "720-771-5337", "Economics and Computer Science");
INSERT INTO User VALUES("Will Wang", "will.wang@duke.edu", "970-820-3302", "Economics");

INSERT INTO Bid VALUES(2015-10-08-29.35.01.021031, 20.0000, "johnancy.kersky@duke.edu", "0684843285", "evelyn.wu@duke.edu", 2015-10-06-07.06.01.121032,32.0991);
INSERT INTO Bid VALUES(2015-10-011-02.05.21.111031, 15.0000, "jake.guo@duke.edu", "1843560283", "bill.wang@duke.edu", 2015-10-10-06.01.11.120032,32.0980);

INSERT INTO Book VALUES("Database Systems: The Complete Book","0684843285", NULL, "like-new", "Jun Yang", 20.0000, "CS316", 2, false, true, NULL, 20.0000, true, evelyn.wu@duke.edu, CURRENT_TIMESTAMP);