Passing a CHAR type variable to to_date

Question

I am loading and transforming some legacy main frame data that stores dates in a Julian format number field, roughly an Oracle RRDDD date format. Some date between 2000 and 2009 drop the leading 0s, for example in 2009, giving a data like 931, which could be Jan 1, 1993 or  Jan 31, 2009. I can stuff a leading zero(s) on the number field to give me '0931' in a char field, which my Oracle top_date will interpret as Jan 31 2009 with the correct mask 'RRDDD." BUT, I cannot find a way to pass my character sting '0931' which is a variable to my my Oracle to_date, which seems to want the enclosing single quotes, even from a character variable:
Thus
my_Julian_date = 345  --  Is February14  ,2003, leading 0's not available from legacy source |
                                                                                                                                                    |
SELECT TO_DATE('00345', 'RRDDD') FROM DUAL    returns 14-FEB-03    OK                     |
SELECT TO_DATE(345, 'RRDDD')      FROM DUAL    returns 14_FEB-03    OK too              |
                                                                                                                                                    |
but if I put my date as character into a variable,                                                                        |
DECLARE my_date VARCHAR2(5);                                                                                         |
BEGIN                                                                                                                                       |
    my_date   := '00345' ;                                                                                                           |
    SELECT TO_DATE(   my_date, "RRDDD') ... fail to read my_date                                     |          /* please ignore that this select from DUAL won't work */
    SELECT TO_DATE('|| my_date||', "RRDDD') ...                                                                  |            /* with the my_date variable, The issue is to_date accepting a variable value */
How can a pass a varchar2 or char VARIABLE  with a VALUE like '00345' to TO_DATE?

Answer 1

Thanks,
but maybe I wasn't good at my description. My source file has a field cit_dte which is a numeric 5 digit representation of a Julian year of form RRDDD. It drops leading zeros for years 2000 to 2009 and would have a value lke  332 for February 1, 2003, or 4365 for 04365, thus resolving to incorrectlly to 65th day of 1943 or 365th day of 2004 with the leading 0,
I need to pass a string like 0421  as a char variable value, my_date, rather than a hard coded string, to to_date like ...
                   TO_DATE(my_char_date,'RRDDD')
rather than TO_DATE('0421','RRDDD')
In your example, you are hard coding the '00345' into to the my_date VARCHAR2 (5) variable but I have to load my_date from a function call IN variable of numbere type, after converting the IN parameter number type to the my_date varchar2 (5) variable.
My flow is  (1.)    NUMBER --> (into function ny_date()  as a number type)
                  (2.)  --> convert parameter IN number type to my_date VARCHAR2(5) variable with leading 0s added as needed (in a case statement)
                  (3.) --> pass variable my_date [character string] to  TO _DATE()
BUT, TO_DATE only seems to accept hard coded character strings. likle '0421' an not a varchar2 variale with a value of 0421. I tried prepedning the parameter into to_date with
...to_date:'||my_date||' , RRDDD) to wrap some single quotes aroudnt he my_date variable value, but that does not work.