@ichisdeno  How does this relate to the original question about combining 3 data sets???   This looks like it should be a completely new topic as your requirements are very different from the original question starting this thread. Also, you seem not to actually want an Append (add records) as an UPDATE, which would replace the values in the master table from a new (transaction) data set based on matching criteria, likely the ID. An update will add new records if the Id is new. If you have corrupted your master data set by creating records with duplicate ids then you need to recover the old version before you start. ... View more