I have two datasets- matching years, different sources. They are matchable by FIPS code, but my problem is 1) that the first data set, from which I am drawing my independent variable data, only has the five-digit FIPS code data, and my other data set has information disaggregated down to the eleven digit level. Any thoughts on combining these more disaggregated data?
You easiest answer is to create a new field in your table with the longer value; than extract the left 5 characters and insert them into the new field. Then you can join on that field without having made any integrity changing updates to the underlying data.
Any database has a function to select a substring of a value.