title: PostgreSQL interval invalidate
body: <pre><code> select date,
      to_char(shares, '99g999g999g999') as shares,
      to_char(trades, '99g999g999') as trades,
      to_char(dollars, 'L99g999g999g999') as dollars
      from facebook
      where date &gt;= '2017-02-01'  + interval '1 months'
      order by date;
  </code></pre>
  <pre class="lang-none prettyprint-override"><code>message: ERROR:  invalid input syntax for type interval: &quot;2017-02-01&quot;
  LINE 6:  where date &gt;= '2017-02-01'  + interval '1 months
  </code></pre>
  <p>I know there is one way to do it by declare a date variable.
  so the code would be</p>
  <pre><code> date &gt;= date: 'Variable' + interval '1 month'
  </code></pre>
  <p>But I don't know how to set a date variable in PGadmin.</p>