PeopleSoft Enterprise

Hi, User_97XVQ
If you want the sub-string of str from the start of the string up to (but not including) the last substring of hyphen-digits-hyphen, then you can use:

REGEXP_SUBSTR ( str
	      , '(.*)-\d+-'
	      , 1
	      , 1
	      , NULL
	      , 1
	      )

If you'd care to post CREATE TABLE and INSERT statements for the sample data, then I could test it.
If str does not contain a sub-0string of all digits surrounded by hyphens, then the expression above returns NULL.

Hi, User_97XVQ
I see that you changed your original message after I replied. Please don't do that: it makes the thread hard to read and your changes easy to miss. Make any corrections and additions in a new reply, at the end of the thread.
If tst is a string containing one or more digits, immediately preceded and followed by a hyphen, then

REGEXP_SUBSTR ( tst
	      , '(.*?)-\d+-'
	      , 1
	      , 1
	      , NULL
	      , 1
	      )

returns the sub-string before the first occurrence of the hyphen-digits-hyphen pattern. The only change for your new requirements is the '?' in the second argument, making '.*' non-greedy (that is, matching as little as possible when there is a choice).
As before, the expression returns NULL if tst does not contain a hyphen-digits-hyphen pattern.