text: /*
    Name: Problem 2609
  	Copyright: 2019 Augusto Machado Ramos
  	Author: Augusto Machado Ramos
  	Date: 07/30/2019
  	Comment language: en
  	Description:
  		As usual the sales industry is doing an analysis of how many products we have in stock, and you can help them.
  		Then your job will display the name and amount of products of each category.
  */
  
  CREATE TABLE categories (
    id numeric PRIMARY KEY,
    name varchar
  );
  
  CREATE TABLE products (
    id numeric PRIMARY KEY,
    name varchar(50),
    amount numeric,
    price numeric(7,2),
    id_categories numeric REFERENCES categories (id)
  );
  
  INSERT INTO categories (id, name)
  VALUES 
    (1,	'wood'),
    (2,	'luxury'),
    (3,	'vintage'),
    (4,	'modern'),
    (5,	'super luxury');
    
  INSERT INTO products (id, name, amount, price, id_categories)
  VALUES 
    (1,	'Two-doors wardrobe', 100,	800,	1),
    (2,	'Dining table',	1000,	560,	3),
    (3,	'Towel holder',	10000,	25.50,	4),
    (4,	'Computer desk',	350,	320.50,	2),
    (5,	'Chair',	3000,	210.64,	4),
    (6,	'Single bed',	750,	460,	1);
    
    /* Solution */
    SELECT categories.name, sum(products.amount) AS sum
    FROM categories
    INNER JOIN products ON categories.id = products.id_categories
    GROUP BY categories.name;
    
    /*  Execute this query to drop the tables */
    -- DROP TABLE categories,products; --
  