retrieve data from more db

HI, I have data on more than 1 db to separate in year name like these: cust2000 --> contain customer infomation in year 2000 cust2001 --> contain customer infomation in year 2001 all db have the same field name. I have put db name and table name in separate file (something like include.php). How I write php code to retrieve my interest value to display in one time? for more help pls describe how to layout compare table in the code. Thank you, SF