title: tables structure for a publication system
body: <p>I have a project to build in-memory database for a publication system and I want a help in the database structure, what will be the structure and fields of the tables and the relations between them.
  the following is an explanation for the database and tables
   In this project, the schema consists of 3 tables: Users, Content, License, sufficient columns should be added to support licenses based on time limits (including perpetual) or number of accesses that give access to specific content slices (a content slice is any criteria that can identify a piece of content such as publication date within a range or a list of content ids and/or a filter on Journal name). </p>
  
  <p>I tried to write 3 tables.</p>
  
  <p>user table and consists of:</p>
  
  <pre><code>-id
  -name
  -password
  -authority
  </code></pre>
  
  <p>license table:</p>
  
  <pre><code>-id
  -name
  </code></pre>
  
  <p>user-license table"</p>
  
  <pre><code>-id
  -user-id (FK)
  -license-id (FK)
  -price
  -expiration date 
  -created at
  </code></pre>