title: MySQL - Mutual exclusion in transactions and locks?
body: <p>I am currently learning about MySQL's transaction and lock features.</p>
  
  <p>Are transactions with the isolation-level <code>SERIALIZABLE</code> and statements between a <code>LOCK</code> and <code>UNLOCK</code> statement on the same table executed mutually exclusive?</p>
  
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  <p><strong>EDIT 1</strong>: For the transaction thing with isolation level <code>SERIALIZABLE</code>, is it even possible to determine whether the transaction is actually mutually exclusive or just the requirements like no phantom reads are fulfilled? Or do these two properties imply the same behavior?</p>
  
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  <p><strong>EDIT 2</strong>: Oh, and are the mechanisms that provide the given isolation-level of a transaction only active if two or more transactions actually work on the same data so that the read phenomena could actually happen?</p>