I have no idea why I would want to solve sudoku in PostgreSQL PL/pgSQL. My guess would be just for the fun of it. I’m also hoping that it can serve as a tutorial example in programming PostgreSQL PL/pgSQL.
So what is sudoku? It is basically a number puzzle where the objective is to fill 9×9 [...]

I’m not sure if many programmers know this. But it’s always a good thing to make sure that they (including me) do. XML specification doesn’t allow ampersand (&). Here’s a quote from W3c.org XML recommendation with bold emphasis added by me.

The ampersand character (&) and the left angle bracket ( 5C’. How would you write [...]

One of the “problem” in using SVN with branches is that you have to figure out which revisions to apply. In most cases, one could not simply take the HEAD version and simply merge that to a branch or TRUNK.
On this page, I’ll attempt to explain why we can’t simply merge the HEAD version. On [...]

This article is an extension of my previous article This time, however, I will write the algorithm completely in PostgreSQL’s PL/pgSQL. For background information and to understand the premise of this post, please glance through my previous post.
Ok now that you’re familiar with what we’re working towards, here’s my assumption of your database structure:

You have [...]

As the final question in one of my interviews a while ago, I was asked to compute the average degrees of separation in social networking site. If you don’t know what degree of separation, here’s an example.
Amy is a friend of Robert. Therefore, Amy and Robert are 1st degree friend. Robert is a friend of [...]