title: when I create table, I got this error ORA-00904: : invalid identifier
body: <p>When I create the table, I got this error <code>ORA-00904: : invalid identifier</code>, I don't know what the error means.</p>
  
  <pre><code>Create table c_stock(s_date date not null,
                       o_stock number(4),
                       add number(4),
                       total number(4));
  </code></pre>