Oracle: Replacing non-numeric chars in a string

Question

I have a field in my database where users have saved free-form telephone numbers. As a result, the data has all sorts of different formatting:

• (area) nnn-nnnn<

Answer 1

You can use REGEXP_REPLACE since Oracle 10:

SELECT REGEXP_REPLACE('+34 (947) 123 456 ext. 2013', '[^0-9]+', '')
FROM DUAL

This example returns 349471234562013.

Alternative syntaxes include:

• POSIX character classes:

  '[^[:digit:]]+'
  

• Perl-influenced extensions (since Oracle 11):

  '\D+'