title: SQL Server table relationship
body: <p>I have to create a database that have flat, flat owner, tenant and bills tables etc.</p>
  <p>The question is when the tenant or flat owner delays bill payment, there will be a %5 extra tax due to delay. First of all I have to create the tables correctly and have to write functions to return the flat, flat owner, tenant (if exists) and the total bill amount with delay tax (if any).</p>
  <p>In final exam I did a table diagram something like this and I failed the exam.</p>
  <p><img src="https://i.stack.imgur.com/VfBcT.png" alt="table relationship diagram" /></p>
  <p>I'm asking you to make correct tables and the query that I asked above. Thank you.</p>