title: SQL - Min difference between two integer fields
body: <p>How I can get min difference between two integer fields(<code>value_0 - value</code>)?
  <code>value_0 &gt;= value</code> always</p>
  
  <pre><code>value_0 | value
  -------------------  
      15  |  10
      12  |  10
      15  |  11
      11  |  11
  </code></pre>