Designing a database interface for programmersMon, Oct 22, 2012 in Databases Programming
How do you connect to and converse with your database of choice (MySQL, in my case)? Chances are it’s largely formed by the programming language you choose. I’ve worked with a variety of programming languages. Anytime I begin learning a new one, I am reminded again that there’s more than one way to skin a cat.
Over the last few years, I’ve mostly programmed in Perl and shell. The shell interface to MySQL is simple: the
mysql command-line tool. There is not much to think about. In Perl, however, the standard is to use DBI. I have grown accustomed to DBI over the years, but that doesn’t mean I like it. I think it’s one of the worst database APIs I’ve seen. The abstractions it uses (there are only two object abstractions: connections and “statement handles”) are awkward to the extreme.
It does get worse, though. PHP historically used libmysql’s C library for connecting to MySQL, and similarly used native drivers/libraries for every other database. You had no notion of abstraction: you called the library’s functions directly. Sure, there were PEAR libraries to wrap around this, but a) they were ugly too, and not really a PHP standard, and b) the language could have done us all a favor and defined a common interface that all of the drivers could be wrapped inside. That’s what every other language tends to do, love it or hate it. When I wrote a lot of PHP, and this was before the newer drivers were available, I wrote a set of classes to abstract away from the raw libmysql C function calls.
Guess what design I chose to emulate for that? Microsoft’s. Microsoft’s database interaction libraries make a lot of sense for me. There’s a notion of a Connection. You can create a Statement that’s tied to the connection, and when you execute the Statement, you get a Result, and so on. This is fairly consistent for VBScript (ASP), Visual Basic, the .NET class libraries, and so on. It is a clean and straightforward design. The functions you want to execute map to verbs you think about, and the nouns/objects are also obvious. You execute a Statement to get a Result.
Think about that in contrast to Perl, where you prepare a Statement against a Database (not a Connection?) and then execute a Statement ($sth) to get… nothing but an indication of whether it succeeded, and then you start retrieving rows from… the $sth? Huh? But rows don’t belong to a Statement, they belong to a Result! Oh, I get it, after I execute a Statement, it shape-shifts into a Result. And then I can re-execute it… bleh. All of the nouns are overloaded with several meanings because there aren’t enough nouns to represent the variety of concepts, and the verbs are attached to the wrong nouns, and it’s just ugly.
Funny enough, I never wrote a sane interface around DBI. (It’s already a wrapper anyway.) I just dealt with it. But I never liked it, and somehow I must have been like the frog in the teapot and never jumped out.
I’m learning a new language now – Go – and it’s time to learn how Go wants me to think about databases. Will it be sane or awkward? I don’t know yet. The documentation doesn’t take any time to introduce it, so I’ll just work through it and see how it’s done.