title: Why default is not used when I set not null contratint?
body: <p>I have table in postgresql database.</p>
  
  <p>For given column I set default value, then I want it to be <code>NOT NULL</code>:</p>
  
  <pre><code>ALTER TABLE "order" ALTER COLUMN last_bill_date SET DEFAULT '-Infinity';
  ALTER TABLE "order" ALTER COLUMN last_bill_date SET NOT NULL;
  </code></pre>
  
  <p>But second statement fails:</p>
  
  <pre><code>ERROR:  column "last_bill_date" contains null values
  </code></pre>
  
  <p><strong>Why <code>DEFAULT</code> value is not used when <code>NOT NULL</code> is applied for this column?</strong></p>