title: Sqlplus pl/sql Date/Time user input understood as bind variable
body: <p>I am facing a strange issue.</p>
  
  <p>I have a small pl/sql anonymous block which prompt the user for a date. I want to re-use this date in a query later, but I get an error like "SP2-0552: Bind variable "01" not declared.".</p>
  
  <p>The issue is that ":01" in the time is interpreted as a bind variable. A workaround is to enter the date between quote '2014/04/16 01:01:01' and not directly 2014/04/16 01:01:01.
  However, I want to be able to enter my date without the quote.</p>
  
  <p>here is a simple script:</p>
  
  <pre><code>declare
      adate VARCHAR2(20);
  begin
      adate := &amp;adate;
      query := 'select to_date(''' || adate ||''', ''YYYY/MM/DD HH24:MI:SS'') from dual';
      dbms_output.put_line(query);
  end;
  
  Enter value for adate: 2014/04/15 01:01:01
  old   4:    adate := &amp;adate;
  new   4:    adate := 2014/04/15 01:01:01;
  SP2-0552: Bind variable "01" not declared.
  </code></pre>