title: add many tables or create parent table
body: <p>I have 7 tables. Each table represents transmission type where each row in table represents the Trasmission.</p>
  
  <p>These are the tables:
  <img src="https://i.stack.imgur.com/7R5eu.jpg" alt="Tables"></p>
  
  <p>Some of the tables have task_reference_id field and some of them doesn't have.<br>
  This means that one task can referenced by many tables.<br>
  No I have to change this structure: Each transmission table with task_reference_id field should reference to many tasks references.<br>
  This means that I need to add 5 tables with fields: task_id, transmission_id that will hold the tasks references.<br>
  But this makes me think, instead of adding 5 new tables maybe I can create parent "Transmission" table that all other tables will "inherit" from (primary key will be foreing key in the parent table).<br>
  And such it will take only one table to make references to tasks. This table will have base_transmission_id, task_id field.</p>
  
  <p>What do you think?
  What will be better: add 5 tables or change the structure with parent table so I will have to add only 1 table in order to reference the tasks?</p>