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CREATE TABLE users ( user_id VARCHAR2(150) PRIMARY KEY );
CREATE TABLE products ( product_id VARCHAR2(300) PRIMARY KEY );
create table downloads (
Download_id varchar2(150) not null,
User_id varchar2(150) references users (User_id),
Download_date date not null,
File_name varchar(300) not null,
Product_id varchar(300) references Products (Product_id)
);