記事http://www.dba-oracle.com/t_extract_comma_delimited_strings_oracle_sql.htmlに従って、これを試してください:
select distinct str from
(select regexp_substr ('ABCD1234, XYZ, ABCD1234, ABCD1234C, ABCD1234, abc, abcX, 1234U, 1234', '[^, ]+',1, rownum) str
from dual
connect by level <= regexp_count ('ABCD1234, XYZ, ABCD1234, ABCD1234C, ABCD1234, abc, abcX, 1234U, 1234', '[^, ]+')) v;
フィドル:http://sqlfiddle.com/#!4 / c858d / 5