title: Relationship Loop in database design
body: <p>I am trying to design a database schema and I have a question im my mind. In my database I have three table (Table(A|B|C)) and TableC refers TableB, Table B refers Table A and Table C refers Table B (C -> B -> A and C -> A). </p>
  
  <p>What I want to know first is, can I consider this a loop and if it is loops are killer or not for DB design (when I consider a directed graph its not, but what about DB design)? Also, is it possible to have loops for a 3NF normalized database?</p>
  
  <p>Moreover, I just want to delete the related rows from Tables B and C when a referenced value is deleted from Table A. Although Table C reference Table B, I do not have a UPDATE/DELETE constraint for this foreign key. Whenever, a row deleted/updated from/on Table A, all related rows in Table B/C should be effected. Is that suitable for referential integrity in terms of not to create multiple paths during cascaded operations from one table to another?</p>
  
  <p>There are good books which had been discusses widely, but still I would be glad if you can recommend good resources about this kind of tips/tricks and practical information.</p>