RE2
syntax
https://regex101.com/
https://regexr.com/
support
REGEXEXTRACT()
Sheet Cheat Sheet -- Regex
Undumb My Data — RegEx Substring Pattern
fetch the phone number as a string of pure digits from a string of a phone number with non-digit characters
NULLIF(TRIM(ARRAY_TO_STRING(REGEXP_EXTRACT_ALL(c.phone, r'\d+'),'')),'') AS phone_number