title: Presto SQL - Combining Columns
body: <p>I am using AWS Athena to run a query against my data set to combine values from different columns found in various data sets (ex. There is a parquet file for each of client 1-4). However, the output is simply empty for &quot;all_clients_total_clicks&quot;. The strange thing is that similar code on another table is working - just not for the one I'm currently working on.</p>
  <p>Can someone please help me confirm whether my syntax is acceptable? Or point me in the right direction/documentation for review? SQL Below:</p>
  <pre><code>SELECT &quot;columnA&quot;,
      sum(&quot;columnX&quot;) AS &quot;TotalImpressions&quot;,
      cast(sum(&quot;client1_column_total_clicks&quot;) AS double)
      + cast(sum(&quot;client2_column_total_clicks&quot;) AS double)
      + cast(sum(&quot;client3_column_total_clicks&quot;) AS double)
      + cast(sum(&quot;client4_column_total_clickss&quot;) AS double) AS &quot;all_clients_total_clicks&quot;
  FROM &quot;db_name&quot;.&quot;db_table&quot;
  Group by &quot;columnA&quot;
  </code></pre>