title: Group Concat in Redshift
body: <p>I have a table like this:</p>
  
  <pre><code>| Col1       | Col2        |
  |:-----------|------------:|
  | 1          |        a;b; |    
  | 1          |        b;c; |
  | 2          |        c;d; |
  | 2          |        d;e; |
  </code></pre>
  
  <p>I want the result to be some thing like this.</p>
  
  <pre><code>| Col1       | Col2        |
  |:-----------|------------:|
  | 1          |       a;b;c;|
  | 2          |       c;d;e;|
  </code></pre>
  
  <p>Is there some way to write a set function which adds unique values in a column into an array and then displays them. I am using the Redshift Database which mostly uses postgresql with the following difference:
  <a href="http://docs.aws.amazon.com/redshift/latest/dg/c_unsupported-postgresql-functions.html" rel="noreferrer">Unsupported PostgreSQL Functions</a></p>