Extract numbers

Question

Hi,
I'm trying to extract just the numbers from these SSN string. Not sure why this expression doesn't work?
WITH T as
(SELECT '222-22-1111' test_string FROM DUAL union all
SELECT '333-33-2222' FROM DUAL union all
SELECT '232-22-2222' FROM DUAL)
SELECT REGEXP_SUBSTR(test_string,'[^-]*') FROM T It only extract the first 3 digits when I need all 9 digits without the dashes.
222
333
232

Answer 1

Hi,
Northstar wrote:
Hi,
I'm trying to extract just the numbers from these SSN string. Not sure why this expression doesn't work?
WITH T as
(SELECT '222-22-1111' test_string FROM DUAL union all
SELECT '333-33-2222' FROM DUAL union all
SELECT '232-22-2222' FROM DUAL)
SELECT REGEXP_SUBSTR(test_string,'[^-]*') FROM T It only extract the first 3 digits when I need all 9 digits without the dashes.
222
333
232
In case you're wondering why you were only getting the first group of digits, the pattern
'[^-]*'means "0 or more of anything except a hyphen".
In each of your strings, that pattern occurs several times. (6 times, to be precise, but that's another question.)
Since you didn't say which occurrance of the pattern you wanted (by passing a 3rd argument to REGEXP_SUBSTR) it defaulted to the 1st occurrance.
When working with regular expressions, it's ofter easier to remove the part you don't want (using REGEXP_REPLACE) than to extract the part you do want (using REGEXP_SUBSTR).
In this case, it's easy enough, and more efficient, to use REPLACE rather than REGEXP_REGLACE, as Sanjay showed you.