title: OUTER JOIN -> want to return something even if empty
body: <p>I try to return a group_concat on 2 tables
  One being my list of schools and the other, some numeric data.</p>
  
  <p>For some dates, i have NO DATA at all in the table SimpleData and so my lEFT OUTER JOINS returns 10 results where i have 11 schools (i need 11 rows for javascript treatment in order too)</p>
  
  <p>here is my query (tell me if i need to give more details about tables</p>
  
  <pre><code> SELECT A.nomEcole, 
      A.Compteur, 
      IFNULL(SUM(B.rendementJour), '0') AS TOTAL, 
      B.jourUS, 
      B.rendementJour
      FROM ecoles A LEFT OUTER JOIN SimpleData B ON A.Compteur = B.compteur
     WHERE jourUS LIKE '2013-07-%'
  GROUP BY ecole
  </code></pre>
  
  <p>in this example, i have no data in SimpleData for this month( not data was recorded at all)</p>
  
  <p>I have to show either NULL or '0' for this missing school and i'm starting to lose my head on something easy apparently :(</p>
  
  <p>Thanks for any help !</p>
  
  <p>olivier</p>