Trim Whitespaces (New Line and Tab space) in a String in Oracle

Question

I need to trim New Line (Chr(13) and Chr(10) and Tab space from the beginning and end of a String) in an Oracle query. I learnt that there is no easy way to trim multiple characters in Oracle. "trim" function trims only single character. It would be a performance degradation if i call trim function recursivelly in a loop using a function. I heard regexp_replace can match the whitespaces and remove them. Can you guide of a reliable way to use regexp_replace to trim multiple tabspaces or new lines or combinations of them in beginning and end of a String. If there is any other way, Please guide me.

Answer 1

If you have Oracle 10g, REGEXP_REPLACE is pretty flexible.

Using the following string as a test:

chr(9) || 'Q   qwer' || chr(9) || chr(10) ||
chr(13) || 'qwerqwer     qwerty' || chr(9) || 
chr(10) || chr(13)

The [[:space:]] will remove all whitespace, and the ([[:cntrl:]])|(^\t) regexp will remove non-printing characters and tabs.

select
    tester,
    regexp_replace(tester, '(^[[:space:]]+)|([[:space:]]+$)',null)
            regexp_tester_1,
    regexp_replace(tester, '(^[[:cntrl:]^\t]+)|([[:cntrl:]^\t]+$)',null) 
            regexp_tester_2
from
    (
    select
        chr(9) || 'Q   qwer' || chr(9) || chr(10) ||
                chr(13) || 'qwerqwer     qwerty' || chr(9) || 
                chr(10) || chr(13) tester 
    from 
        dual
    )

Returning:

• REGEXP_TESTER_1: "Qqwerqwerqwerqwerty"
• REGEXP_TESTER_2: "Q qwerqwerqwer qwerty"

Hope this is of some use.