Using regular expressions will help you do some advanced querying and data manipulation. I've mostly used them in PostgreSQL.

I don't have any examples of code, but I have an uncompleted Javascript project where I use them a lot.

Here's some code that is a regular expression that will do forward and reverse lookups for “Book Chapter Verse(s)” ranges. This is Javascript here, but the patterns themselves won't change.

// Find all the range strings
var pattern = "";

// pattern = pattern + "(Genesis|Leviticus) *";
pattern = pattern + "(" + p_book_titles + "|" + p_book_short_titles + ") *";

// Match Book c:v which is *always* the initial string
var chapter_verse = "(\\d+:\\d+)";
pattern = pattern + chapter_verse;

// Match possible Book c:v-v, c:v-v,v, c:v,v-v,v
var following_verses = "(((( ?- ?|, ?)?\\d+)*(?!:))*)?";
pattern = pattern + following_verses;

// Start all over again
pattern = pattern + "(( ?(-|,|;) ?)?";
pattern = pattern + chapter_verse + following_verses + ")*";

var re = new RegExp(pattern, 'g');