Terminology is definitely at issue here.
A FileMaker "Database" is actually a group of 1 or more Files--each of which can contain 1 or more Tables.
So it appears thate you have two different Tables linked by a name field (Linking tables by a name field is most often not the best option..)
But from there there is a distinct lack of detail as to what you have and what you want to do. If you want to copy data from a field in one table to a field in another, we need to answer this question first: "into WHICH records in the related table do you want to copy this data?" Is there one and only one related record in table 2 linked to the current record in table 1? Do you want to put this data into a new record that is also linked to the current record of table 1? Something else?
I recommend that you take a step back and, from a user's perspective, describe exactly what it is that you want to do here.
If I have a "Found" list of names in DB! to use this process on, would I need a script?
Possibly, possibly not. It's even possible at this point that you shouldn't be copying any data at all....
Ok. Here goes.
I am the registrar for Iris (the flower) names. Each year I create a new file for that years registrations. Also in that file are names from previous year registrations that are offered for sale in the current year (those entries are called Introductions).
I have a separate file that is a compendium of all regiatrations. I update the compendium at the end of each registration year with the new registration records through a manual export/import process.
However, currently I have to manually enter the Introduction information into the compendium. (Please remember I did not create this system)
Assume the following fields:
Registration file: IrisName, Introduction year, Introducer
Compendium file: IrisName, Intro_Year, Intro_By
So the logic would be:
First Find the set of introduction records in Registration file (that is easy), then
If the Registration file: IrisName is found in Compendium file: IrisName
then for each specific matched record pair:
Registration file:Introduction year gets copied to Compendium file:Intro_Year and
Registration file:Introducer gets copied to Compendium file:Intro_By
I don't follow how that is supposed to work for you. If these are newly introduced varieties, why would they exist at all in the compendium file? If they are NEW, they shouldn't yet exist in that table....
The Introductions are names that were Registered in prior years and so were put in the compendium at the end of that registration year.
The record fields in the compendium look roughly like:
Name, Creator, Description, parentage, Registration year, Introducer, Intro year
With the last to fields empty until subsequent years when introduction is made (if ever)
From here, it is quite possible that you don't need two tables for this. (Functionally speaking, it makes little difference if your tables are in the same file or different files. What is important is whether or not you have linked them in a relationship.) It looks to me like you could use the same table for both purposes and this would eliminate the need for what you are having to do manually.
But working with what you currently have in place, you need to link the two tables in a relationship. If these two tables are defined in separate files instead of both in the same table, you have an extra step to take in this process: In your Registrations file, open Manage | Database | Relationships and click the new table occurrence button (far lower left corner) to open a dialog for adding a new table occurrence box to the relationships graph. Select "add FileMaker Data Source" from the drop down, find your Compendium file, open it, and then select the compendium table. You have now created a "table occurrence" that refers to the compendium table from your compendium file. Drag from the name field in this new occurrence to the name field for your Registrations occurrence to link them in a relationship. (if both tables are in the same table, you only need to do what is described in the previous sentence.)
Now you can go to your registrations layout and use the field tool to add fields from the Compendium table to it. You will be able to add data directly to those fields just as though they are part of one and the same table. Once you have copied over any data from existing records to these fields, you can delete those fields from your registration table and just use the fields in the compendium table. If you enable "allow creation of records via this relationship". You can use the process of entering data into a field from the compendium table on your registration layout as the way to create a new record in the compendium table.
And if you decide to keep this data in fields of both tables, a script can use the Set Field step to copy data from a field in Registrations into a specified field in Compendium.
I apologize for being so slow to reply. Your answer was great. It took me a bit to figure things out but I have a working solution.