New triggers, increased decimal sizes, clean up

shop.sql

@@ -23,9 +23,9 @@ insert into user_role(id, role) values (2, 'admin');
 
 create table user_statistics(
 	id int primary key,
-	total_gains decimal(6,2) not null default 0.00,
+	total_gains decimal(64,2) not null default 0.00,
 	sell_count int not null default 0,
-	total_spent decimal(6,2) not null default 0.00,
+	total_spent decimal(64,2) not null default 0.00,
 	purchase_count int not null default 0,
 	foreign key (id) references user(id)
 );
@@ -34,15 +34,15 @@ create table product(
 	id int primary key auto_increment,
 	seller_id int not null,
 	name varchar(32) not null,
-	price_pc decimal(6,2) not null,
+	price_pc decimal(12,2) not null,
 	image blob not null,
 	image_name varchar(64),
 	foreign key (seller_id) references user(id)
-);
+) auto_increment = 13001;
 
 create table cart(
 	id int primary key,
-	price_total decimal(6,2) not null default 0.00,
+	price_total decimal(24,2) not null default 0.00,
 	item_count int not null default 0,
 	foreign key (id) references user(id)
 );
@@ -52,7 +52,7 @@ create table cart_item(
 	cart_id int not null,
 	product_id int not null,
 	count int not null,
-	price_subtotal decimal(6,2) not null,
+	price_subtotal decimal(12,2) not null,
 	date_added datetime default current_timestamp,
 	foreign key (cart_id) references cart(id),
 	foreign key (product_id) references product(id)
@@ -62,8 +62,9 @@ create table purchase(
 	id int primary key auto_increment,
 	user_id int not null,
 	purchase_time datetime default current_timestamp,
-	price_total decimal(6,2) not null,
-	was_successful tinyint(1) not null,
+	price_total decimal(24,2) not null default 0.00,
+	item_count_total int not null default 0,
+	was_successful tinyint(1) not null default 0,
 	foreign key (user_id) references user(id)
 );
 
@@ -72,53 +73,30 @@ create table purchase_item(
 	purchase_id int not null,
 	product_id int not null,
 	count int not null,
-	price_subtotal decimal(6,2) not null,
+	price_subtotal decimal(12,2) not null,
 	foreign key (purchase_id) references purchase(id),
 	foreign key (product_id) references product(id)
 );
 
+-- Create / Delete statistics with user creation / deletion
+
 create trigger after_user_insert
-after insert
-on user for each row
+after insert on user
+for each row
 begin
 	insert into user_statistics(id) values (new.id);
 	insert into cart(id) values (new.id);
 end;
 
 create trigger after_user_delete
-after delete
-on user for each row
+after delete on user
+for each row
 begin
 	delete from user_statistics where id = old.id;
 	delete from cart where id = old.id;
 end;
 
-create trigger after_cart_insert
-after insert
-on cart_item for each row
-begin
-	update cart
-	set price_total = (
-		select sum(price_subtotal)
-		from cart_item
-		where cart_id = new.cart_id
-	)
-	where id = new.cart_id;
-end;
-
-create trigger after_cart_delete
-after delete
-on cart_item for each row
-begin
-	update cart
-	set price_total = ifnull(
-		(select sum(price_subtotal)
-		from cart_item
-		where cart_id = old.cart_id),
-		0.00
-	)
-	where id = old.cart_id;
-end;
+-- Calculate subtotal of a cart item automatically
 
 create trigger calculate_price_subtotal
 before insert on cart_item
@@ -130,3 +108,133 @@ begin
 		where p.id = new.product_id
 	);
 end;
+
+create trigger calculate_price_subtotal_on_update
+before update on cart_item
+for each row
+begin
+	set new.price_subtotal = (
+		select new.count * p.price_pc
+		from product p
+		where p.id = new.product_id
+	);
+end;
+
+-- Check for buying from self
+
+create trigger check_for_buying_from_self
+before insert on cart_item
+for each row
+begin
+	declare seller_id_check int;
+
+	select seller_id into seller_id_check
+	from product
+	where id = new.product_id;
+
+	if new.cart_id = seller_id_check then
+		signal sqlstate '45000'
+		set message_text = 'Cannot insert into cart_item. Seller_id and cart_id must be different.';
+	end if;
+end;
+
+-- Cart price updates
+
+create trigger after_cart_insert
+after insert on cart_item
+for each row
+begin
+	update cart
+	set price_total = (
+		select sum(price_subtotal)
+		from cart_item
+		where cart_id = new.cart_id
+	),
+	item_count = (
+		select sum(count)
+		from cart_item
+		where cart_id = new.cart_id
+	)
+	where id = new.cart_id;
+end;
+
+create trigger after_cart_update
+after update on cart_item
+for each row
+begin
+	update cart
+	set price_total = (
+		select sum(price_subtotal)
+		from cart_item
+		where cart_id = new.cart_id
+	),
+	item_count = (
+		select sum(count)
+		from cart_item
+		where cart_id = new.cart_id
+	)
+	where id = new.cart_id;
+end;
+
+create trigger after_cart_delete
+after delete on cart_item
+for each row
+begin
+	update cart
+	set price_total = ifnull(
+		(select sum(price_subtotal)
+		from cart_item
+		where cart_id = old.cart_id),
+		0.00
+	),
+	item_count = ifnull(
+	(select sum(count)
+		from cart_item
+		where cart_id = old.cart_id),
+		0
+	)
+	where id = old.cart_id;
+end;
+
+-- Update statistics on purchase
+-- TODO Finish me
+
+create trigger on_purchase_update_stats
+after insert on purchase_item
+for each row
+begin
+	declare seller_id int;
+	declare buyer_id int;
+
+	select product.seller_id
+	into seller_id
+	from product
+	inner join purchase_item
+	on new.product_id = product.id
+	limit 1;
+
+	select purchase.user_id
+	into buyer_id
+	from purchase
+	inner join purchase_item
+	on new.purchase_id = purchase.id
+	limit 1;
+
+	-- Update buyers statistics
+	update user_statistics
+	set total_spent = total_spent + new.price_subtotal,
+	purchase_count = purchase_count + new.count
+	where user_statistics.id = buyer_id;
+	
+	-- Update sellers statistics
+	update user_statistics
+	set total_gains = total_gains + new.price_subtotal,
+	sell_count = sell_count + new.count
+	where user_statistics.id = seller_id;
+
+	-- Update purchase
+	update purchase
+	set item_count_total = item_count_total + new.count,
+	price_total = price_total + new.price_subtotal
+	where id = new.purchase_id;
+end;