The question is, what do you want to happen if that value is not in both tables? What do you want as the output? INNER join only works if it's both tables, if it's one and not the other then you would need to use a LEFT/RIGHT JOIN. Personally, I almost never use an INNER join, I use right/left instead that way if missing values are present they would have missing values and it's an obvious error that's easier to notice. If you use an inner join and accidentally drop a category that's much harder to know. ... View more

You modify your code to append to an existing data set stored in a permanent location. You need to decide how many checks you need for your process as well - for example do you ever need to handle rollbacks, do you need to deal with cases where you may need to run it multiple times a day? I separate my reporting/data management processes so this isn't an issue typically. See an example here:   https://gist.github.com/statgeek/353374a5d8ea4f0c89ce5d80a47f4a4c ... View more