Oracle: Friendly URLs

On the one hand, we want to avoid hitting the database if we don’t have to. On the other hand, if we can use built-in functions in our queries, this can be preferable to manipulating the data after it’s been returned from the database. For example, writing this:

SELECT emp_id, INITCAP(fname) AS fname, INITCAP(lname) AS lname
  FROM emp

is certainly* better than writing this:

SELECT emp_id, fname, lname
  FROM emp

and then using your development tool to capitalize the names after the data have already been returned (in CF it would look something like this: ucase(left(fname, 1)) & lcase(mid(fname, 2, len(fname) – 1)) – clunky!!).

*As long as your database queries need not be portable.

A better example still would be the following:

SELECT emp_id, COALESCE(dept_id, 0) AS dept_id
  FROM emp

instead of:

SELECT emp_id, dept_id
  FROM emp

With the latter I have to check to see if dept_id is non-null before displaying, while with the former I can simply display as-is.

What does this have to do with friendly URLs? Friendly as in SEO-friendly. The URL is very important in search engine optimization. Suppose we have a table of articles as in a previous post:

SELECT id, title, description, pubdate, journal_name, author_name, num_reads
  FROM articles

We would like to have the article’s title in the URL. The conventional wisdom is to use hyphens (-) as word separators. We also don’t want any weird characters that are going to be url-encoded. The solution (or, at least, “a” solution) is to use regular expressions to get rid of unusual characters and replace spaces with hyphens. And here Oracle is truly our friend:

SELECT id, title, description, pubdate, journal_name, author_name, num_reads
     , REGEXP_REPLACE(REGEXP_REPLACE(LOWER(title), '[^-a-z0-9/ ]', ''), '[/ ]', '-') AS url_keyword
  FROM articles

The inner REGEXP_REPLACE replaces every character that is not (a) alphanumeric, (b) a space, or (c) a hyphen or forward slash with a null string. The outer one replaces forward slashes and spaces with hyphens. What is left over is bunches of alphanumeric characters (hopefully, words) separated by hyphens – in other words, an SEO-friendly URL string.