title: Select rows where two or more (flags) columns are ON
body: <p>I have a table like this:</p>
  
  <pre><code>+----+-------+-------+-------+
  | Id | Flag1 | Flag2 | Flag3 |
  +----+-------+-------+-------+
  |  1 |     0 |     0 |     1 |
  |  2 |     0 |     0 |     0 |
  |  3 |     1 |     1 |     1 |
  |  4 |     1 |     1 |     0 |
  +----+-------+-------+-------+
  </code></pre>
  
  <p>How can I select the rows which has any two or more flags on?</p>
  
  <p>In this example the query should select rows with Id: <code>3 and 4</code></p>