title: Unexpected keyword UNION in bigquery
body: <p>I'm trying to run a UNION query like this:</p>
  
  <pre><code>#standardSQL
  SELECT
      s.campaign_name, 
      date(event_date) as event_date,
      'email' medium,
      count(s.send_id) sends
      from pixel_logs.table1 s
      inner join pixel_logs.full_logs AS l on l.uid = s.uid
      where 1=1
      group by
      event_date,
      campaign_name
      order by
      event_date
  
  UNION ALL
  
      select
      s.campaign_name,
      date(event_date) as event_date,
      'sms' medium,
      count(s.send_id)
      from pixel_logs.table2 s
      inner join pixel_logs.full_logs AS l on l.uid = s.uid
      where 1=1
      and account_id = 'xxxx'
      group by
      event_date,
      campaign_name
      order by
      event_date;
  </code></pre>
  
  <p>But I'm getting this message:</p>
  
  <pre><code>Syntax error: Unexpected keyword UNION at [21:1] Dismiss
  </code></pre>
  
  <p>How to fix this?</p>