Statement contains an OUTPUT clause without INTO clause error
I think it may be related to what Anthony Horne wrote.
Does this work?
ALTER TRIGGER [dbo].[Trigger_RootIdUpdate] ON [dbo].[Messages] AFTER INSERTAS BEGIN UPDATE Messages SET Messages.RootId = INSERTED.MessageId FROM Messages Msg JOIN INSERTED ON Msg.MessageId = INSERTED.MessageId WHERE Msg.MessageId = INSERTED.MessageId AND INSERTED.RootId = 0;END