Populate custom field with given xml/tabel

[Deleted user]

Hi,

I want to try to populate custom fields of multiple issues given external data in form of a table (excel / xml / whatever).
The usecase:
I have issues given a certain Number xxxxx and want to populate another field of this issue with a string, given by the external table for example:

000001, Name, String;

000002, Name2, String2;

....

If my Issue-Field has the Number 000001, I want the custom field to populate with "String" given an external source.
Any ideas how to do this?Or how to implement the xml for usage in Jira?

We currently have Jira automation, Scriptrunner and jmwe at our disposal.
Regards