title: How to query on mysql prompt to distinguish between NULL and "NULL" (varchar)?
body: <p>I've got this row when querying a <code>unit</code> table:</p>
  <pre><code>mysql&gt; select * from unit where id=136\G;
  *************************** 1. row ***************************
                                       id: 136
                             canonical_id: 0
                               digit_code: 136
                               ascii_code: dBm
                                     name: decibel-milliwatts
                                   symbol: dBm
                               multiplier: NULL
                                   offset: NULL
                                canonical: 1
                                     temp: NULL
  </code></pre>
  <p>But when running mysqldump for the same row I've got this:</p>
  <pre><code>INSERT INTO `unit` VALUES (136,0,135,'dBm','decibel-milliwatts','dBm','NULL','NULL',1,'NULL');
  </code></pre>
  <p>As you can see the <code>NULL</code> values are actually strings with the content <code>'NULL'</code> what is not visible from the terminal.</p>
  <p>Is there anyway to get something like this where querying from the prompt?</p>
  <pre><code>                                 id: 136
                         canonical_id: 0
                           digit_code: 136
                           ascii_code: 'dBm'
                                 name: 'decibel-milliwatts'
                               symbol: 'dBm'
                           multiplier: 'NULL'
                               offset: 'NULL'
                            canonical: 1
                                 temp: 'NULL'
  </code></pre>