title: Getting a ORA-01722: invalid number even though there is no attempt to convert a varchar2 to a number
body: <p>The query is a bit long</p>
  
  <pre><code>select user_aud_view.audit_id,
  user_aud_view.user_id,
  (users.last_name_txt || CHR(44) || users.first_name_txt) as user_name,
  user_aud_view.column_name_txt,
  user_aud_view.old_value_txt,
  user_aud_view.new_value_txt,
  case when evaluator.country_id like '%CAN%' then to_char(user_aud_view.audit_last_updated_dt,'YYYY/MM/DD HH12:MI:SS AM')
  else to_char(user_aud_view.audit_last_updated_dt,'MM/DD/YYYY HH12:MI:SS AM') end as    audit_last_updated_dt ,
  user_aud_view.audit_updated_user_id,
  evaluator.evaluator_name_txt,
  evaluator.evaluator_id,
  TRIM(TO_CHAR(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'Month'))||' '||TO_CHAR(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'dd'||','||' yyyy') AS DAILY_TXT,
  trim(to_char(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'Month')) || ' ' || to_char(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'yyyy') AS MONTHLY_TXT,
  decode(to_char(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'Q'),1,'January - March',2,'April - June',3,'July - September',4,'October - December') || ' ' || to_char(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'yyyy') AS QUARTERLY_TXT,
  to_char(to_evaluatortime(user_aud_view.audit_last_updated_dt,115) ,'yyyy') AS YEARLY_TXT
  from user_aud_view,
  users,
  evaluator
  WHERE user_aud_view.evaluator_id = evaluator.evaluator_id
  and user_aud_view.user_id = users.user_id
  and user_aud_view.audit_last_updated_dt &gt;= to_dbtime(to_date('07/01/2012', 'mm/dd/yyyy'),115)  and user_aud_view.audit_last_updated_dt &lt; to_dbtime(to_date('08/01/2012', 'mm/dd/yyyy'),115)   AND ( (user_aud_view.evaluator_id = 115) )   ORDER BY user_id ASC, user_id ASC
  </code></pre>
  
  <p>It complains about the error on this line:</p>
  
  <pre><code>and user_aud_view.audit_last_updated_dt &gt;= to_dbtime(to_date('07/01/2012', 
  'mm/dd/yyyy'),115)  and user_aud_view.audit_last_updated_dt &lt; to_dbtime(to_date('08/01/2012', 'mm/dd/yyyy'),115)   
  AND ( (user_aud_view.evaluator_id = 115) )   ORDER BY user_id ASC, user_id ASC
                                                                      *
  </code></pre>
  
  <p>ERROR at line 21:
  ORA-01722: invalid number</p>
  
  <p>However, user_id is a VARCHAR2 field. </p>
  
  <p>I am not aware of the data in those fields, because we don't have access to this client's database. </p>