title: how to design entities in typeorm if there is a center user table and different role tables
body: <p>suppose I am designing a school website, and there are many roles,like students , teachers, admins...</p>
  
  <p>my DB design looks like this</p>
  
  <p><a href="https://i.stack.imgur.com/Q0nNm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Q0nNm.png" alt="enter image description here"></a></p>
  
  <p>then, consider easy to read and easy to save how to design entities in typeorm is better?</p>
  
  <p>[UPDATED]
  finally, i design like this,i just merge all role into a ROLE table,and role_type means different role, eg. 5 means admin, 3 means teacher, 2 means student.</p>
  
  <p>however, there are 2 columns redundancy, the school_id and the class_id.
  these 2 columns are not necessary to admin, cause admin does not belong to any one school or class, but if i try to places these 2 columns in to othere tatble to record, that seems another kind of waste and complex more 
  <a href="https://i.stack.imgur.com/UrbrK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UrbrK.png" alt="enter image description here"></a></p>