A couple of more examples of the same:
SELECT trim(regexp_substr('Err1, Err2, Err3', '[^,]+', 1, LEVEL)) str_2_tab
FROM dual
CONNECT BY LEVEL <= regexp_count('Err1, Err2, Err3', ',')+1
/
SELECT trim(regexp_substr('Err1, Err2, Err3', '[^,]+', 1, LEVEL)) str_2_tab
FROM dual
CONNECT BY LEVEL <= length('Err1, Err2, Err3') - length(REPLACE('Err1, Err2, Err3', ',', ''))+1
/
Also, may use DBMS_UTILITY.comma_to_table & table_to_comma: http://www.oracle-base.com/articles/9i/useful-procedures-and-functions-9i.php#DBMS_UTILITY.comma_to_table