oraclesql:如何使用regexp\将令牌带到两个或更多列

如果streetnum存在,如何使用oracle regexp\*str拆分它?目标是使视图V\u MY\u USERS具有3列ID、STREET\u NUM、STREET\u NAME。

MY_USERS - that has two columns

ID    STREET_ADDRESS
-------------------- 
1     991 My Street  # Some records start with street number followed by space
2     Don street     # some records do not have street num, => null

ID    STREET_NUM       STREET_NAME
----------------------------------
1     991              My Street            
2     null             Don street