title: Oracle sql combination
body: <p>I have table with this result (just for example, actually it has more records):</p>
  
  <pre><code>31.3.2020   A  1
  30.4.2020   A  2
  31.3.2020   B  1
  30.4.2020   C  3
  </code></pre>
  
  <p>Is possible to add there empty missing values by sql?
  In this case:</p>
  
  <pre><code>30.4.2020   B  0
  31.3.2020   C  0
  </code></pre>
  
  <p>Thanks</p>