title: Does EntityFramework have the ability to check and not overwrite other people changes?
body: <p>What I mean is as follows:</p>
  
  <p><strong>Machine A</strong> editing customer A, <strong>Machine B</strong> also opened customer A information for editing.  </p>
  
  <p>After <strong>Machine A</strong> updated customer A's information, <strong>Machine B</strong> clicked Save and overwrote the changes with the old information.</p>
  
  <p>Can Entity Framework do some checking and throw an exception before Save? I think I read something about non-optimistic concurrency somewhere...</p>