>Unfortunately I need to tap the data from an off the shelf product and can't change the structure of the tables. It is using VFP 3.0 and I don't think it is in a dbc. Any other suggestions?

There are no built in functions for this. You'l have to write code that loops through the records, and loops through the fields, relating on a primary key, comparing the contents. You're right- this is going to be slow on lots of data.