DROP TABLE Sales;
DROP TABLE Product;
DROP TABLE Customer;
DROP TABLE Provider;
DROP TABLE Demo;

CREATE TABLE Product
(
  id_prod INTEGER NOT NULL PRIMARY KEY,
  Name VARCHAR2(4000),
  Price DOUBLE
);

CREATE TABLE Demo(
  id_demo INTEGER NOT NULL PRIMARY KEY,
  Name VARCHAR2(4000),
  Parent INTEGER,
  FOREIGN KEY (Parent) REFERENCES Demo
);

CREATE TABLE Customer(
  id_c INTEGER NOT NULL PRIMARY KEY,
  Name VARCHAR(4000),
  id_demo INTEGER,
  FOREIGN KEY (id_demo) REFERENCES Demo
);

CREATE TABLE Provider(
  id_p INTEGER NOT NULL PRIMARY KEY,
  Name VARCHAR2(4000),
  id_demo INTEGER,
  FOREIGN KEY (id_demo) REFERENCES Demo
);

CREATE TABLE Sales(
  id_prod INTEGER NOT NULL,
  FOREIGN KEY (id_prod) REFERENCES Product,
  id_c INTEGER NOT NULL,
  FOREIGN KEY (id_c) REFERENCES Customer,
  id_p INTEGER NOT NULL,
  FOREIGN KEY (id_p) REFERENCES Provider,
  Q INTEGER,
  date_s DATE NOT NULL
);

ALTER TABLE Sales ADD PRIMARY KEY (id_prod, id_c, id_p, date_s);