SQL - transform a date string

Question

Hello,
I have scenario where I need to transform a date string in SQL (from "yyyy-mm-dd" to "dd/mm/yyyy"):
E.g My table EMPTABLE looks like this
EMPNO STARTDATE(string)
1111 2000-11-30
2222 1998-01-22
I need an output of
EMPNO STARTDATE(string)
1111 30/11/2000
2222 22/01/1998
I know that we can user "to_date" and "to_char" functions to do that. The query would look like:
SELECT EMPNO as EMPNO, to_char(to_date(STARTDATE,'yyyy-mm-dd'),'mm/yy/dddd') as STARTDATE from EMPTABLE;
Are there any other ways to achive this? Like just using string manipulation.
Why I'm asking with the above query if there is any data discrepancy (e.g for one record the month value is 25 by mistake), the query fails.
Any help is appreciated.
Thanks.
Edited by: kIDMan on Nov 20, 2009 7:29 AM

Answer 1

Hi,
Welcome to the forum!
A lot of folks store dates in DATE columns; then it just takes one TO_CHAR call to get them in any format, and invalid data is impossible.
You can use SUBSTR to extact parts of the string, and || to re-assemble them in a different order.
Starting in Oracle 10, you can also use regular expressions, like this:
,     REGEXP_REPLACE ( startdate
                        , '([0-9]{4})-'     ||     -- \1 = year
                              '([0-9]{2})-'     ||     -- \2 = month
                   '([0-9]{2})'          -- \3 = day
                        , '\3/\2/\1'
                        )          AS startdate_dmyIf startdate does not contain the pattern (4 digits, hyphen, 2 digits, hyphen, 2 digits), the the expression above will return startdate unchanged.
Edited by: Frank Kulash on Nov 20, 2009 1:11 PM