REGEXP_LIKE help - escaping the hyphen

Question

I need to match string that does not contain "dc-ba" - all are literal. It has to return true for all strings that is not "ab-cd".
The hypen is creating the problem. If hypen were not there:
select ('Matched') "Status" from dual where REGEXP_LIKE('def', '[^(^dcba$)]');
Matchedselect ('Matched') "Status" from dual where REGEXP_LIKE('dcba', '[^(^dcba$)]');
no rows returnedEverything is as required to this point, but when I try to apply the same with hypen:
select ('Matched') "Status" from dual where REGEXP_LIKE('dc-ba', '[^(^dc-ba$)]');
Error: ORA-12728: Invalid range in regular expression
If I try to escape the hyphen:
select ('Matched') "Status" from dual where REGEXP_LIKE('dc-ba', '[^(^dc\-ba$)]');
MatchedWhich sould not be the case. It shoudl match all string other than "dc-ba".
Am I doing something wrong?

Answer 1

Tubby,
it is not just a question of replacing all the hyphens with something that's "special" that won't mess with the regular expression. First of all, that "special" can never occur in source data. For example, replacing hyphens with tilda could result in rejecting dc~ba:
SQL> select ('Matched') "Status" from dual where REGEXP_LIKE(REPLACE('dc~ba', '-','~'), REPLACE('[^(
^dc-ba$)]', '-','~'));
no rows selected
SQL> Secondly, there is over a dozen special meaning characters in regular expressions, so each of them must be replaced with a chatacter that can not appear in source data.
SY.