title: SQL query merge two columns from two tables in one column of resulting table?
body: <p>I have the following tables:</p>
  
  <p>T1</p>
  
  <pre><code>  ID 
    1
    2
    3
  </code></pre>
  
  <p>T2</p>
  
  <pre><code>ID  SERVICE
  1   PSTN
  1   ADSL
  3   ADSL
  </code></pre>
  
  <p>T3</p>
  
  <pre><code>ID   DEV
  1    3G
  3    2G 
  </code></pre>
  
  <p>I want as output </p>
  
  <pre><code>ID  SERVICE/DEV
  1      PSTN
  1      ADSL
  1      3G
  2
  3      ADSL
  3     2G
  </code></pre>
  
  <p>How to merge this?</p>
  
  <p>I can not use classic <code>LEFT OUTER JOIN</code>.</p>
  
  <p>Total number in output table for one id should be the summary of <code>T2+T3 (FOR ID=1 2+1=3)</code> but for <code>ID=2</code> it also should exist in table output with blank second column.</p>