Pentaho CDE "All" option in "Select" component
<p>While a "Select All" feature in a select dropdown component would seem to be a straightforward feature, I've had an incredibly hard time finding a workable solution. I can find three SO questions on the topic, but none of the approaches work entirely.   </p>

<p><a href="https://stackoverflow.com/questions/25639546/how-to-add-a-select-all-option-to-select-component-in-cde?rq=1">How to add a select all option to select component in CDE</a><br>
<a href="https://stackoverflow.com/questions/37474549/pentaho-cde-reset-parameter/37999391#37999391">Pentaho CDE reset parameter</a><br>
<a href="https://stackoverflow.com/questions/38213674/how-to-add-a-select-all-option-to-select-component-in-cde?rq=1">How to add a &quot;select all&quot; option to select component in CDE?</a>  </p>

<p>I have a table with a column that contains ratings from 1-5 (as string-type). I need to give users the option to select either a value from 1-5 or an "All".</p>

<p>I created a simple datasource (DB2) pulling in the numbers 1-5 as strings. When applicable below, I would <code>UNION ALL</code> with a <code>''</code> or an "All"</p>

<p><code>SELECT ... WHERE (CAST(RATING AS CHAR) = CAST(${parameter} AS CHAR) OR ${parameter} =  '')</code></p>

<p><code>SELECT ... WHERE (RATING = ${parameter} OR ${parameter} =  '')</code></p>

<p><code>SELECT ... WHERE (RATING LIKE (CASE WHEN ${parameter} = 'All' THEN '%' ELSE ${parameter} END))</code></p>

<p>I use the "Select Component" and "Simple Parameter" features as would be expected. I've experimented with setting the "Parameter Property Value" equal to <code>''</code>, "All", and numbers 1-5, but I can only get <strong>either</strong> the "All" <strong>or</strong> the numeric selections to work. In probably 50 iterations of this methodology, I've never once successfully had <strong>both</strong> work.</p>

<p>Is there a simple or straightforward way to add an "All" selection without switching to a multi-select component or additional JavaScript? </p>