What are good regular expressions?

Question

I have worked for 5 years mainly in java desktop applications accessing Oracle databases and I have never used regular expressions. Now I enter Stack Overflow and I see a lot of

Answer 1

As you may know, Oracle now has regular expressions: http://www.oracle.com/technology/oramag/webcolumns/2003/techarticles/rischert_regexp_pt1.html. I have used the new functionality in a few queries, but it hasn't been as useful as in other contexts. The reason, I believe, is that regular expressions are best suited for finding structured data buried within unstructured data.

For instance, I might use a regex to find Oracle messages that are stuffed in log file. It isn't possible to know where the messages are--only what they look like. So a regex is the best solution to that problem. When you work with a relational database, the data is usually pre-structured, so a regex doesn't shine in that context.