text: insert into customers(id, first_name, surname) values fred, durst;
  
  update customers set first_name='', surname="" where id=2;
  
  delete from customers where id=;
  
  select * from orders join order_items on orders.id=order_items.order_id join items on order_items.item_id=items.id;
  
  insert into orders(customer_id) values (2), (3), (4);
  
  insert into items(item_name, price) values ("fanta", 1.50), ("coke", 1.50), ("dr pepper", 1.50), ("water", 0.75);
  
  insert into customers(first_name, surname) values ("bob", "smith"), ("jess", "parkes"), ("helen", "mirren"), ("brad", "pitt"), ("george", "clooney");
  
  insert into order_items (order_id, item_id) values (4, 1), (5, 2), (6, 3);
  insert into order_items (order_id, item_id, quantity) values (4, 3, 6);
  select * from order_items;
  
  select * from order_items;
  
  select sum(price) as Order_Cost from (select item_id from order_items where order_id =4) as items_in_order join items on items_in_order.item_id = items.id;
  
  insert into orders(customer_id, total_price) values (4, (select sum(price) as Order_Cost from (select item_id from order_items where order_id =4) as items_in_order join items on items_in_order.item_id = items.id));
  select * from orders;
  
  update orders set customer_id=3, total_price=
  	(select sum(price) as Order_Cost from (select item_id from order_items where order_id=4) as items_in_order
      join items on items_in_order.item_id = items.id where id=2)
      where id=4;
  select * from users;
  
  select * from orders join order_items on orders.id=order_items.order_id;
  
  update users set username=pineapples where id=2;
  
  update order_items set item_id="
  				+ order.getItemId() + " where order_id=" + order.getId()
                  
                  update orders set customer_id=3, total_price=(select sum(price) as Order_Cost from (select item_id"
  				+ "from order_items where order_id =" + order.getId() 
  				+ ") as items_in_order join items on items_in_order.item_id = "
  				+ "items.id where id=" + order.getId() + ") where id=" + order.getId()
  select * from orders;
  insert into orders(customer_id, total_price) values (
  	2, (select sum(price) as Order_Cost from 4 as items_in_order join items on items_in_order.item_id=items.id));
      
  select * from order_items;
  
  insert into orders(customer_id, total_price, quantity) values (
  	3, (select sum(price)*5 as Order_Cost from (
  	select item_id from order_items where order_id=5) as items_in_order join items on items_in_order.item_id = items.id), 5);
      
  insert into orders(customer_id, total_price, quantity) values (3, (select sum(price)*5 from items where id=order.getItemId()), 5);
  