title: How to concat query results?
body: <p>I've got data like this:</p>
  
  <pre><code>A          | B
  -----------------------
  Date       | Data
  30/06/2015 | 1.2
  01/07/2015 | 2
  01/07/2015 | 3
  02/07/2015 | 2
  02/07/2015 | 3
  </code></pre>
  
  <p>And I write a simple query like this:</p>
  
  <pre><code>=query(A:B; "select YEAR(A) || ' ' || month(A), SUM(B)
      group by YEAR(A), month(A)")
  </code></pre>
  
  <p>But I've got a "Value Error", so I write this</p>
  
  <pre><code>=query(A:B; "select YEAR(A), MONTH(A), SUM(B)
      group by YEAR(A), month(A)")
  </code></pre>
  
  <p>And it work well, but, how can I concat two values in one cell ?</p>
  
  <p>I though of this:</p>
  
  <pre><code>=QUERY(Journal!A:B;"select A, SUM(B)
      group by A
      format A 'yyyy-MM'")
  </code></pre>
  
  <p>But the format operation is done AFTER the group by so it's like the group by never was.</p>
  
  <p>Any idea ?</p>
  
  <p>[Solution]</p>
  
  <pre><code>=query({Arrayformula(text(Foo!A:A; "yyyy-MM")) \Foo!B:B}; "select Col1, sum(Col2) group by Col1"; -1)
  </code></pre>
  
  <p>Because my local is "french" I've to use the '\' in the Arrrayformula and ; instead of ','...</p>