title: Default value for column postgres function with argument
body: <p>I have a postgres function that takes one argument. I want to make this function the default value for a column, but I'm not sure how to pass the argument into the table definition.</p>
  
  <p>This is what I mean, I have two columns in the table that look like this:</p>
  
  <pre><code>trade_id INTEGER NOT NULL
  group_id INTEGER DEFAULT trade_id_f(argument_goes_here);
  </code></pre>
  
  <p>I want to make the <code>DEFAULT</code> value of <code>group_id</code> to be the return value of <code>trade_id_f(trade_id)</code> where <code>trade_id</code> is the <code>trade_id</code> of the record to be inserted.</p>
  
  <p>I'm new to all things postgres functions, is this possible?</p>