Hey @Matt_M! Can you share how that Orders table is set up? That error looks like it's complaining about a foreign key constraint. Not sure what data type that column is, but you should be able to set up an array type column if you create the table through SQL.
Create Table:
Insert data from multiselect, and display select * results in a table in the Retool app:
They key syntax is placing { } around the multiselct value.