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 FLOAT
    );

    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);

    DROP SEQUENCE ProdSeq;
    DROP SEQUENCE CustSeq;
    DROP SEQUENCE ProvSeq;

    CREATE SEQUENCE ProdSeq
      START WITH 1
      INCREMENT BY 1;

    CREATE SEQUENCE CustSeq
      START WITH 1
      INCREMENT BY 1;

    CREATE SEQUENCE ProvSeq
      START WITH 1
      INCREMENT BY 1;

    INSERT INTO Product VALUES (ProdSeq.nextval, 'Potato', 56.0);
    INSERT INTO Product VALUES (ProdSeq.nextval, 'Macaroni', 325.0);
    INSERT INTO Product VALUES (ProdSeq.nextval, 'C-400', 9999999999999.0);
    INSERT INTO Product VALUES (ProdSeq.nextval, 'Vodka', 100.0);
    INSERT INTO Product VALUES (ProdSeq.nextval, 'Salo', 200.0);
    INSERT INTO Product VALUES (ProdSeq.nextval, 'Yaga', 60.0);

    INSERT INTO Demo VALUES (1, 'РФ', NULL);
    INSERT INTO Demo VALUES (2, 'Северо-Кавказский', 1);
    INSERT INTO Demo VALUES (3, 'Центральный ФО', 1);
    INSERT INTO Demo VALUES (4, 'Приволжский', 1);
    INSERT INTO Demo VALUES (5, 'Чеченская республика', 2);
    INSERT INTO Demo VALUES (6, 'Республика дегестан', 2);
    INSERT INTO Demo VALUES (7, 'Московская область', 3);
    INSERT INTO Demo VALUES (8, 'Смоленская область',3);
    INSERT INTO Demo VALUES (9, 'Пермский край', 4);
    INSERT INTO Demo VALUES (10,'Республика татарстан', 4);

    INSERT INTO Provider VALUES (ProvSeq.nextval, 'ОАО "Равшан"', 7);
    INSERT INTO Provider VALUES (ProvSeq.nextval, 'ЗАО "Светские Колбасы"', 7);
    INSERT INTO Provider VALUES (ProvSeq.nextval, 'ООО "ААА"', 3);
    INSERT INTO Provider VALUES (ProvSeq.nextval, 'ОАО "Африканские Гостинцы""', 2);
    INSERT INTO Provider VALUES (ProvSeq.nextval, 'ЗАО "Крошка Антошка"', 2);

    INSERT INTO Customer VALUES (CustSeq.nextval, 'Типичный потребитель', 9);
    INSERT INTO Customer VALUES (CustSeq.nextval, 'Пермское представительство Аль-Каеды',9);
    INSERT INTO Customer VALUES (CustSeq.nextval, 'Приволжский закупщик', 4);
    INSERT INTO Customer VALUES (CustSeq.nextval, 'ПриветОтвет', 4);
    INSERT INTO Customer VALUES (CustSeq.nextval, 'Джигит', 5);
    COMMIT;