but i dont have to :), look at the skeleton plugin and look how the BOL folder is set up.
That is how you get data from your tables.
To get data from another table you can just put the sql in your bol service file which is the lazy and not so good way (i have learned that over time myself)
or the proper way,
at the top of your service file add the BOL call for that other table class and then just return that BOL in your statement.
php file function -> service file -> dao -> return service file -> return php file funciton
all of us including me are guilty of just sticking stuff in the service file and not using the dao as its intented, i learned late how to use the dao and im trying to correct it as i update my stuff. So basically your sql goes in the dao file. Now sometimes especially if you are getting data from another table then you can put your sql in the service file and its ok because you dont need to make a dao for another table outside your plugin. Remember the dao is for each table of your plugin. So each table has its own dao file.