Tag Archives: dbic

DBIC vs DBI

Three times in the last few months I’ve had the “DBIC or raw DBI” discussion. People have told me that they don’t use DBIC because raw DBI is better. And each time, the person promoting DBI in the discussion has used an argument that boils down to “DBIC is probably useful for people who don’t know SQL very well”.

I find that argument really puzzling. Not least because I like to think that I know more than a little about SQL. SQL is a skill that that has run through my career for longer than Perl. I’ve been using SQL since I left college in 1988. I only started using Perl in about 1996. And yet, although I still consider myself a bit of an expert in SQL, I use DBIC for pretty much all of the database work I do these days – and have done for about five years.

I use DBIC not because I don’t understand SQL. I use it because it makes my life easier. I use it because it frees up some of the time I used to spend dealing with the minutia of database communication so that I can spend it working on other, more interesting, parts of my project.

When I’m running training courses that introduce DBIC I have slide that is entitled “SQL is Boring”. It’s a joke of course but, like all the best jokes, it gets a laugh because there’s more than a little truth in it. There are, of course, many interesting SQL problems. I’ve spent many an enjoyable (if slightly frustrating at the time) hour trying to coax the right data out of complex query with correlated subqueries, outer joins and aggregated functions. But that’s the exception rather than the rule.

The vast majority of the SQL I write for the applications I work on is incredibly boring. It’s  boring because it’s all so similar. You get the data to present a list of objects to the user. The user selects the object they’re interested in, so you select all the data about that object. You might select some data about related objects. The user changes some of that data, so you update that row in the database. On a good day, you might delete an object from the database. Or insert a new one. Most of the SQL you need is like that. It’s boring.

We have computers to do the boring work for us. So let the computer generate all that boring SQL. Free up your time to work on the gnarly and interesting problems.

But that’s not the only advantage of using DBIC (or some other ORM). Think about the data that you get back from the database. The data you get back from a DBI call is an array. Or perhaps a hash. Or maybe a multi-dimension data structure if you’re using one of DBI’x more complex fetch() methods. But it’s still a dumb variable. From DBIC, I get an object. An intelligent variable. A variable that knows how to react to various messages. A variable that will save any changes back to the database automatically without me having to worry about where it came from and making sure that I’m writing it back to the right place.

I’m not saying for a second that there’s no place for DBI any more. For a start, DBI underlies DBIC so it’s still a vital part of our toolkit. And of course I still use it for quick one-off scripts. But when those scripts are still hanging round being used and maintained three months later (as they always are) I’ll rewrite them to use DBIC.

If you want to write large applications that are going to be easy to maintain and extend, then you should really be using DBIC (or something similar). I don’t care how well you know SQL. DBIC will make your life easier.

I’ve just mentioned a couple of reasons why I think that DBIC makes my life easier. I’m sure I’ve missed important stuff. What do you think? Why do you use DBIC instead of DBI?

Modern Perl in Linux Format

A couple of times, I’ve complained here about the standard of Perl articles in the British magazine Linux Format.

Following the second of those articles I got into a discussion with Graham Morrison, the editor of the magazine and he offered me the opportunity to improve matters by writing my own short series of tutorials for them.

The first of those tutorials appears in issue 151 of the magazine which will be appearing in UK newsagents about now.

The series is called “Modern Perl” (in an attempt to distance it from their earlier tutorials) and the first article is about how easy it is to write a database application using DBIx::Class. The second article will take the same database and build it into a simple web application using Dancer. That will hopefully be in issue 153 (skipping an issue). There will probably be a third article in the series which will add features to the web application.

I’ll find out what my rights are to the articles and hopefully I’ll be able to put them on the web at some point in the future.

If you see a copy in your newsagents then please consider picking it up. And if you enjoy the article, then please let the magazine know.