title: Is a primary key required in this particular scenario?
body: <p>I have a name table with (id,first_name,middle_name,last_name,sex)
  and an email table with (id_fk,email_add)</p>
  
  <p>Infact I will be having similar tables of the second kind, like a phone table (id_fk,phone_no), where id_fk is the foreign key referring to the id in the name table.</p>
  
  <p>Is it required or rather is there a good reason to have a primary key in the second and third tables? Or other similar tables? Or would you suggest a different schema?</p>
  
  <p>PS: The tables are for a contact storing app</p>