I would like to retrieve a sequence of numbers in between two strings. The text may have other numbers and I only want to get the sequence in between 'item ' and ' n' (first occurrence). Also, the length of the sequence can vary.

The following is what I have tried:

```
SELECT REGEXP_SUBSTR(clob_text, 'item ([0-9]+?) n') AS my_number FROM my_table WHERE something = something;

```

However it returns the value "item 123456789 n", and I want only the number value.

I have also tried the regex '\item ([0-9]+?) \n' which returns the same, and '(?=item )([0-9]+?)(?= n)' and '\item /([0-9]+?)/ \n', that returns nothing.

At last, I tried to intercalate the expressions and it worked but is not ideal:

```
SELECT REGEXP_SUBSTR(REGEXP_SUBSTR(clob_text, '\item ([0-9]+?) \n'), '[0-9]+') FROM ...

```

How can I remove these unwanted characters so the result would be only "123456789" with one expression only?

Example input:
'Somdasdas dasd sdaisdjas asod dasdhjs 1564, dasdohndsdias sdasdasdasdasds,
ddissd ksdnas skid as 5645 sdnaslndas, ndsadn ndasknd dnsd: sdas 5465 asdasd
dnaskldnas ojsd (dasdksdas) asdklhasdas dsd. isdjasdsdpoojs asdasdasdasdsad
46564 iasdonsoi sdjosd kjlsdk kkpnasd item 12345879 não-existente da lista 14
sdasdnsd jdspka 2564 sadasds.'

Expected output:
'12345879'