title: Create a calculated field using data from another tables
body: <p>I'm creating a database design for only a subject school. My current design is showed in the next link:</p>
  
  <p><a href="https://i.stack.imgur.com/C8QUQ.png" rel="nofollow noreferrer" title="Click to enlarge"><img src="https://i.stack.imgur.com/C8QUQ.png" alt="Database design" title="Click to enlarge"></a>
  </p>
  
  <p>I've enclosed three entities and all of then contains calculated fields:</p>
  
  <ul>
  <li>StudetExams: Average</li>
  <li>StudentExamObjectives: Accredited and Score</li>
  <li>ObjectiveGrades: FinalScore</li>
  </ul>
  
  <p>But they need to interact with another tables. For example, StudentExamObjectives use a Score field, where is the avg for all the problems correct in Answers table, then accredited is 1 if Score values is above or equals than 0.70.</p>
  
  <p>I don't know if my design is wrong or I need to do a trick to get those values.</p>
  
  <p>Thanks in advance.</p>