I'm designing a fun little web app and one of the challenges I've run in to was abstracting away the sql. My reasons to do so is two fold. The first is that I wish to be as database agnostic as I possibly can and the best way to achieve this seems to me to abstract out the sql, the actual part that interfaces with the database, in to a small class I could just swap in an out, for example: User_data_mysql and User_data_postgre and User_data_flatfiles. My second reason is just one of elegance.. it always seemed inelegant and messy to have random bits of sql strewn around.

After pondering it for a while, I've come up with two ideas. My first idea is that I could write database accessing functions in the form of one for each table for each type of database. Eg I would have a function like User_Data_Mysql::get_data; and I could pass it things like: get_data(['name','id','pw'],{order_by=>'id'}); but the problem there is that writing a function like that quickly becomes horrendously complicated to the point where it feels like I just rewrote sql, except in perl and much uglier. I suppose with proper planning this function wouldn't be too grotesque but I basically feel that $sql="select foo,baz,bar from qux where foo=1 and baz=2 order by bar limit 0,20" is much cleaner then say,  qux::get_data([qw/foo baz bar/],order=>{foo=>1},limit=>[0,20]);

My second option seems to me to just write all sql I would need and store them in functions, eg:  sub get_user_data_by_id; sub get_user_data_by_name; sub get_user_data_by_date; and so on and so forth. I could just wrap these functions in a module with whatever database they apply to and just do mysql::get_user_data_by_name; but of course this is A) massively inelegant and B) seems terribly fragile and just plain ugly.

In reply to Abstracting sql by BUU

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