title: Oracle/SQL: invalid number format model when concatenating a date and a time into a single date value
body: <p>I am trying to create a trigger in Oracle that compares two dates and then deletes records if the difference of the two dates falls below a certain value. I have a full date value with the format 'DD-MON-YYYY HH24MI' and then for the second date value, I want to concatenate a 'DD-MON-YYYY' value with a 'HH24MI' value.</p>
  
  <p>The problem I am getting is that when I try to concat the date and time value together using to_char, and then using to_date on that returned value, it gives me a ORA-01481 invalid number format error. The relevant lines from the trigger itself are below. If anyone can help me out with this, it would be greatly appreciated! </p>
  
  <pre><code>CREATE OR REPLACE TRIGGER dateTrig
  ...
  DECLARE
      day date;
      ftime date;
      CURSOR c_table1 IS SELECT ...;
  BEGIN
  FOR entry IN c_table1 LOOP
      day := to_date(entry.fdate);
      ftime := to_date(to_char(day, 'DD-MON-YYYY') || ' ' || to_char(entry.dtime, 'HH24MI'), 'DD-MON-YYYY HH24MI'); -- this is the line that is causing the error
      dbms_output.put_line(day || ', ' || ftime);
  END LOOP;
  END;
  /
  </code></pre>