This more of a Q/A question, perhaps someone is facing the same problem, so I'll ask a question and then answer it.
Say that we have a table defined as:
CREATE TABLE T (x BIGINT NOT NULL GENERATED ALWAYS AS IDENTITY);
and need to generate one row for each row in another table. For one row we could use:
INSERT INTO T (x) VALUES (DEFAULT);
INSERT INTO T (x) SELECT DEFAULT FROM SRCTABLE
does not work, and generates the following error:
SQL0206N "DEFAULT" is not valid in the context where it is used. SQLSTATE=42703
How do I add multiple rows to such table without resorting to a cursor?