title: Sql query returns duplicate
body: <p>I have executions and each execution has several images and videos, example,</p>
  
  <p>table execution</p>
  
  <pre><code> id |    name
   1   execution1
  </code></pre>
  
  <p>table image</p>
  
  <pre><code>id |   executionId | image
  1          1          'path'
  2          1          'path2'
  </code></pre>
  
  <p>table audio</p>
  
  <pre><code>id |   executionId | audio
  1          1          'path3'
  </code></pre>
  
  <p>I want a query that get all the executions, with each execution having all their images like,</p>
  
  <pre><code>  { executions: [
           { id: 1,
             name: execution1,
             images: 'path+path2',
             audio: 'path3'
            },
           {...}
        ]
   }
  </code></pre>
  
  <p>I have this query:</p>
  
  <pre><code> query = 
      "select a.id, group_concat(image.image SEPARATOR '+'), group_concat(audio.audio SEPARATOR '+') 
      from execution a 
      left join image on image.executionId = a.id 
      left join audio on audio.executionId = a.id 
      group by a.id";
  </code></pre>
  
  <p>but returns</p>
  
  <pre><code>  { executions: [
           { id: 1,
             name: execution1,
             images: 'path+path2',
             audio: 'path3+path3'
            },
           {...}
        ]
      }
  </code></pre>
  
  <p>Why ?</p>