SQL & PL/SQL

Hello,

I have a specific string with more than 9 regex capture groups. When I apply the regexp_substr function and set the sub_expression value to 10 or higher, it always returns null. Here is the question: Is it possible to have more than 9 capture groups in Oracle regular expression when applying the regexp_substr function?.

Example: The following regular expression function will return the 9th capture group, in this case the letter "l"

SELECT REGEXP_SUBSTR('helloworld','(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})',1,1,NULL,9) FROM DUAL;

If I want to extract the letter "d", which is group 10, the function returns null

SELECT REGEXP_SUBSTR('helloworld','(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})(.{1})',1,1,NULL,10) FROM DUAL;

Can someone please clarify this?

Thanks.

Pablo C.