regexp_substr function
Applies to:  Databricks SQL 
 Databricks Runtime 11.3 LTS and above
Returns the first substring in str that matches regexp.
Syntax
regexp_substr( str, regexp )
Arguments
- str: A- STRINGexpression to be matched.
- regexp: A- STRINGexpression with a pattern.
Returns
A STRING.
The regexp string must be a Java regular expression.
String literals are unescaped. For example, to match '\abc', a regular expression for regexp can be '^\\abc$'.
In case of a malformed regexp the function returns an INVALID_PARAMETER_VALUE error.
If either argument is NULL or the pattern is not found, the result is NULL.
Examples
SQL
> SELECT regexp_substr('Steven Jones and Stephen Smith are the best players', 'Ste(v|ph)en');
 Steven
> SELECT regexp_substr('Mary had a little lamb', 'Ste(v|ph)en');
 NULL
> SELECT regexp_substr(NULL, 'Ste(v|ph)en');
 NULL
> SELECT regexp_substr('Mary had a little lamb', NULL);
 NULL