title: Creating a one-to-one relationship between tables with an existing one-to-many relationship
body: <p>So I have these two tables in my database:</p>
  
  <pre><code>Companies
  --------------------
  CompanyID (PK)
  Name
  
  
  Employees
  --------------------
  EmployeeID (PK)
  CompanyID (FK)
  Name
  </code></pre>
  
  <p>Basically, one company has many employees.</p>
  
  <p>But I'd like to have each company have exactly one employee who is the Main Contact. My initial thought was to just add a <code>MainContactID</code> field to the <code>Companies</code> table that references the <code>EmployeeID</code> in <code>Employees</code>, but that would create a loop with the relationships.</p>
  
  <p>What's the best way to do this?</p>