I have a function that is set up to write to a database with 10-20 standard variables with 10 fields each, but the application is going to a place where database access is not available. Can Mathematica read an Excel file and pick up the portions of the file that relate to one of these 20 variables, change them if needed and write the whole thing back again? If so, how would that be accomplished? Thanks!
According to the comments you have several options:
I would also like to add that Mathematica comes with a built in, standalone, database called HSQL. Wherever Mathematica exists that database also exists and I wonder if perhaps you missed this when you said that you cannot use databases where this code is going. There is an example of how to set up an HSQL database as well as many example queries here.