joins within a merge table

[patrick felt]

i'm wondering if there is a way for me to go a merge table across multiple databases and have joins still be coherent. i've got several databases that have identical tables and structure but different data within those tables. i've got an application that needs data from all the databases at the same time. the easiest solution from a development standpoint is to have a merge table of each table in each database and just do a select * (as opposed to select * union select * .... a ton of times). the only problem is that i have tables that may have different data for a given id. something like a table of students and a table of student types where the types might be different.

is there a way to get a join to actually join the tables the right way, or is the merge engine just not the right way to go on this one? what would you all suggest i look into if this isn't the right way. i'd like to keep queries for the developers easy, but if there is no other way then i'll have to tell them to write crazy long queries.

thanks!

pat