title: Database design efficiency with 1 to many relationships limited 1 to 3
body: <p>This is in mysql, but its a database design issue. If you have a one to many relationship, like a bank customer to bank-accounts, typically you would have the table that records the bank-account information have a foreign key that keeps track of the relationship between account and customer. Now this follows the 3rd normal form thing and is a widely accepted way of doing it.</p>
  
  <p>Now lets say that you are going to limit a user to only having 3 accounts. The current database implementation will support this and nothing would need to change. But another way to do this would have 3 columns in the account table that have the id of the 3 respective accounts in them. By the way this violates 1st normal form of db design. </p>
  
  <p>The question is what would be the advantage and disadvantages of having the user account relationship recored in this way over the traditional?</p>
  
  <h3>Update</h3>
  
  <p>Unfortunately I am not in-charge of the db design. When I saw a similar relationship implemented in our db, I asked my boss, the db designer, why he choose to do it that way. I didn't really get a strait answer, or an answer I understood to have logical reasons backing it up. "This is a very common relationship when you work with databases allot, and that is just how you do it." I asked for more clarification. ... Didn't get me anywhere and made him defensive.</p>
  
  <p>Thank you all so much for these post, I couldn't really find any books that even talked about doing something like this. I found lots of books tell me to do it the right way but not many giving an example this broken and then explaining why it will suck.</p>