title: Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT clause?
body: <p>Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause?</p>
  
  <pre><code>CREATE TABLE `foo` (
    `ProductID` INT(10) UNSIGNED NOT NULL,
    `AddedDate` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    `UpdatedDate` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
  ) ENGINE=INNODB;
  </code></pre>
  
  <p>The error that results:</p>
  
  <blockquote>
    <p>Error Code : 1293</p>
    
    <p>Incorrect table definition; there can
    be only one TIMESTAMP column with
    CURRENT_TIMESTAMP in DEFAULT or ON
    UPDATE clause</p>
  </blockquote>