Re: Need regexp help (seemingly simple problem)
Date: Sun, 25 Oct 2009 20:31:51 +0100
small addendum to the Jared's solution - in case there can be more such digit sequences in the string
select '2B4a12345Z2la6789ZraxxxZyaZZa45aaZZZ7' source
- want from 'a' to 'Z'
, regexp_replace('2B4a12345Z2la6789ZraxxxZyaZZa45aaZZZ7','^.*a([[:digit:]]+)Z.*$','\1',1,1) last_occurence
, regexp_replace('2B4a12345Z2la6789ZraxxxZyaZZa45aaZZZ7','^.*?a([[:digit:]]+)Z.*$','\1',1,1) first_occurence
, regexp_replace('2B4a12345Z2la1234567ZraxxxZyaZZaa45aZZZ7','a([[:digit:]]+)Z|a|[^a]*','\1 ',1,0) all_occurences
from dual ; SOURCE LAST_OCCURENCE FIRST_OCCURENCE ALL_OCCURENCES ------------------------------------- -------------- --------------- --------------------------- 2B4a12345Z2la6789ZraxxxZyaZZa45aaZZZ7 6789 12345 12345 1234567
1 rows selected
See http://forums.oracle.com/forums/thread.jspa?threadID=668970 for further details of the all_occurences solution.
- Original Message ----- From: Jared Still To: michaeljmoore_at_gmail.com Cc: oracle-l_at_freelists.org Sent: Friday, October 23, 2009 8:10 PM Subject: Re: Need regexp help (seemingly simple problem)
The [:digit:] class actually need to be written as [[:digit:]].
Here's an example using regexp_replace
select '2B4a12345Z2lr7' source
- want from 'a' to 'Z' , regexp_replace('2B4a12345Z2lr7','^.*a([[:digit:]]+)Z.*$','\1',1,1) target , regexp_replace('2B4a12345Z2lr7','^.*a(+)Z.*$','\1',1,1) target from dual /
12:09:39 ordevdb01.radisys.com - js001292_at_dv11 SQL> /
SOURCE TARGE TARGE
- ----- ----- 2B4a12345Z2lr7 12345 12345
1 row selected.
On Fri, Oct 23, 2009 at 11:01 AM, Michael Moore <michaeljmoore_at_gmail.com> wrote:
First of all I would like to say that finding detailed information about Oracle's implementation of regular expressions is next to impossible. Either that, or I am looking in all the wrong places. So, links to any complete online documentation would be appreciated. I found plenty of 'basic explanation' but there has got to be more.
Here is the specific problem I am trying to solve using REGEXP_SUBSTR. I have a string that might look something like this:
'2B4a12345Z2lr7' . I want to extract the 12345. In words, find the first letter 'a' and return all the digits up to the letter Z.
There can be any number of random non-'a' characters prior to the initial 'a' and likewise after the letter Z. In other words, in my example, '2B4' just represents some random sequence of characters, as does '2lr7'.
I could easily use INSTR and SUBSTR to do this, but my goal is to solve the problem using a single REGEXP_SUBSTR statement. Also, I have used the pattern 'a[[:digit:]]+' which results in 'a12345'. This is almost right, but I don't want the 'a' to be returned.