regexp_extract function
Applies to:  Databricks SQL 
 Databricks Runtime
Extracts the first string in str that matches the regexp expression and corresponds to the regex group index.
Syntax
regexp_extract(str, regexp [, idx] )
Arguments
- str: A- STRINGexpression to be matched.
- regexp: A- STRINGexpression with a matching pattern.
- idx: An optional integral number expression greater or equal 0 with default 1.
Returns
A STRING.
The regexp string must be a Java regular expression.
When using literals, use raw-literal (r prefix) to avoid escape character pre-processing.
regexp may contain multiple groups.
idx indicates which regex group to extract.
An idx of 0 means matching the entire regular expression.
Examples
SQL
> SELECT regexp_extract('100-200', '(\\d+)-(\\d+)', 1);
 100