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select regexp_substr(name, '[^,]+', 1, 1) as parent_name,
regexp_substr(name, '[^,]+', 1, 2)
from (select 'ab,cd' as name from dual union all select 'ef' from dual) t
| PARENT_NAME | REGEXP_SUBSTR(NAME,'[^,]+',1,2) |
|---|---|
| ab | cd |
| ef | null |