title: Sequence as default value for a column
body: <p>I have already created a sequence:</p>
  
  <pre><code>create sequence mainseq as bigint start with 1 increment by 1
  </code></pre>
  
  <p>How do I use this sequence as the default value of a column?</p>
  
  <pre><code>create table mytable(
      id      bigint not null default mainseq     -- how?
      code    varchar(20) not null
  )
  </code></pre>