title: One-to-one mapping confusion
body: <p>Why is it that a lot of people are referring to One-to-One when I am sure they are referring to Many-to-one?</p>
  
  <p>For instance, if you have two tables;</p>
  
  <pre><code>Inventory (InventoryID)    
  Item (ItemID, InventoryFK)
  </code></pre>
  
  <p>There is no one-to-one mapping here as far as I can tell. It's "Many items to one inventory". </p>
  
  <p>Now, let's assume that there would be only <strong>one</strong> item per inventory. In this case, my colleagues would start calling it a "one-to-one". Am I correct in pointing out that it's <strong>still</strong> a many-to-one relationship? When I try to explain this to them they don't seem to understand.</p>
  
  <p>I believe a proper one-to-one mapping to be something like this:</p>
  
  <pre><code>Person (Column: PersonID, Name)
  PersonAddress (Column: PersonID, StreetName, StreetNumber)
  </code></pre>
  
  <p>Here you'd have two tables, sharing the exact same PK.</p>
  
  <p>Assuming my assumptions are correct, why are so many people abusing the term "one-to-one"?</p>