title: check if table-column contains at least one value != 0
body: <p>I have a table like this:</p>
  
  <pre><code>id   |   name   |  priceEUR  | priceCHF  | priceUK  | priceRUB
  --------------------------------------------------------------
  1    |   00A    |      0     |     0     |     0    |     0
  2    |   00B    |     10     |     0     |     0    |     0
  3    |   00C    |      0     |     0     |    20    |     0
  4    |   00D    |      0     |     0     |     0    |     0
  5    |   00E    |      0     |    50     |     0    |     0
  6    |   00F    |      0     |     0     |     0    |     0
  7    |   00G    |      0     |     0     |     0    |     0
  8    |   00H    |     12     |     0     |     0    |     0
  9    |   00I    |      0     |    13     |    70    |     0
  ..   |   ...    |     ..     |    ..     |    ..    |    ..
  n    |   99Z    |      0     |     1     |     0    |     0
  </code></pre>
  
  <p>I need to know for each column if the column, in the entire table, holds <strong>at least one</strong> <code>price != 0</code>, so the result should be something like this:</p>
  
  <pre><code>priceEUR  |  priceCHF  |  priceUK  |  priceRUB
  ----------------------------------------------
      10    |    50      |    20     |    0
  </code></pre>
  
  <p>It's not important that the returned value is the highest in the column, I need only to know if for that specific price there's one <code>value != 0</code>.</p>
  
  <p>Please note that those columns have type <code>TEXT</code>. It's possible to achieve this result in just one query?</p>