title: JSON VIEW using GROUP_CONCAT question
body: <p>Hey DBAs and overall smart dudes.  I have a question for you.</p>
  
  <p>We use MySQL VIEWs to format our data as JSON when it's returned (as a BLOB), which is convenient (though not particularly nice on performance, but we already know this).</p>
  
  <p>But, I can't seem to get a particular query working right now (each row contains NULL when it should contain a created JSON object with the values of multiple JOINs).</p>
  
  <p>Here's the general idea:</p>
  
  <pre><code>SELECT CONCAT(
    "{",
       "\"some_list\":[", GROUP_CONCAT( DISTINCT t1.id ), "],",
       "\"other_list\":[", GROUP_CONCAT( DISTINCT t2.id ), "],",
    "}"
  ) cool_json
  
  FROM table_name tn
  
  INNER JOIN ( some_table st ) ON st.some_id = tn.id
  
  LEFT JOIN ( another_table at, another_one ao, used_multiple_times t1  )
   ON st.id = at.some_id AND
      at.different_id = ao.different_id AND
      ao.different_id = t1.id
  
  LEFT JOIN ( another_table2 at2, another_one2 ao2, used_multiple_times t2  )
   ON st.id = at2.some_id AND
      at2.different_id = ao2.different_id AND
      ao2.different_id = t2.id
  
  GROUP BY tn.id ORDER BY tn.name
  </code></pre>
  
  <p>Anybody know the problem here?  Am I missing something I should be grouping by?  It was working when I was only doing 1 LEFT JOIN &amp; GROUP_CONCAT, but now with multiple JOINs / GROUP_CONCATs it's messing it up.</p>
  
  <p>When I move the GROUP_CONCATs from the "cool_json" field they work as expected, but I'd like my data formatted as JSON so I can decode it server-side or client-side in one step.</p>