title: SQL QUERY with SUM
body: <p>please help Im juste starting  with SQL</p>
  
  <p>Given the following table:</p>
  
  <pre><code>CUSTOMER     TRANSACTION_CODE     AMOUNT
  --------     ----------------     -------
  001           WE01                 100.00
  001           WE02                  80.00
  002           WE01                 120.00
  002           WE02                  22.00
  </code></pre>
  
  <p>I want to the SQL query to sum up transaction for same customer ( I dont need to display TRANSACTION CODE)</p>
  
  <pre><code>CUSTOMER      AMOUNT
  --------     --------- 
  001           180.00
  002           144.00
  </code></pre>
  
  <p>I did different test with <code>group by</code>and <code>SUM</code> but I cannot get the proper syntax - your help is appreciated like always</p>