First, use RegexBuddy to define a regex or retrieve a regexp saved in a RegexBuddy library. Rely on RegexBuddy's clear regex analysis, which is constantly updated as you build the pattern, rather than dealing with the cryptic regex syntax on your own. Detailed help on that syntax is always only a click away.
If you copied a regex written for another programming language or database, simply paste it into RegexBuddy, and select the original regex flavor. RegexBuddy will then automatically convert it to the POSIX ERE regex flavor when you generate a Oracle source code snippet.
If you created a new regular expression, test and debug it in RegexBuddy before using it in your Oracle queries. Test each regex in RegexBuddy's safe sandbox without risking precious data. Quickly apply the regex to a wide variety of input and sample data, without having to produce that input through your database.
Finally, let RegexBuddy generate a source code snippet that you can copy and paste directly into whichever database application you use. Just choose what you want to use the regex for, and a fully functional code snippet is ready. You can change the names of tables and columns to suit your naming style or the current situation, which RegexBuddy automatically remembers.
Don't bother trying to remember Oracle's specific regexp syntax. And don't worry about properly escaping backslashes and other characters. Just tell RegexBuddy what you want to do, and you will get the proper Oracle code straight away.