IF EXISTS (SELECT 1 FROM inserted i join deleted d on i.id = d.id WHERE i.word != d.word OR i.levenshtein_distance != d.levenshtein_distance OR i.parent_node_id != d.parent_node_id OR ...

join BK_Tree b on cn.id = b.parent_node_id where b.levenshtein_distance >= dbo.F_Levenshtein(cn.word, @search_word) - @tolerance and b.levenshtein_distance <= dbo.F ...