I am processing lots of files with student assessment data.  For one project I have to merge cases from ~120 different files.

Each file is for a different grade, language of test, and administration (e.g., Math3Eng1_2011, Math3Sp1_2011, Math4Eng1_2011, Math5-1_2011, Math6_2011).  Each school year there are 26-34 different files.  I want to be able to easily/efficiently merge the cases from all files for a particular school year.  To make matters more complicated, the file naming structure changes year to year.  I don’t want to merge files one at a time because a total of over 5M records exist and it takes forever to do 25+ data passes.  I don’t know how to merge multiple files in one data pass unless I hard coded the # of files to merge (but this varies).  

I could take a directory listing via windows command prompt, then using an editor add the prefixes and suffixes to each line so it can be pasted into a merge statement, but I wanted a more automated process.  

Anybody have a good suggestions?