Hi, I have run the following query in a query node in over 500 process ins

Hi,
I have run the following query in a query node in over 500 process instances without an error:
INSERT INTO tempAbsenceClientUpload SELECT FirstName, LastName, UserID, UserIsActive, Email, TopClient, ClientGroup, isUpdated, MainProcessID, rownumber FROM temporaryAbsClientTable

which simply takes from one table to another.
However, I now get the following error message: 'Subquery returns more than 1 row Error'
Can anyone help me to understand why?

I don't really want alternative code suggestions- just why it happened.

Thanks...

OriginalPostID-77203

OriginalPostID-77203