I would like to know if I can run a request like that:
INSERT INTO t2 (a, b) VALUES ( SELECT a, b FROM `t1` AS o WHERE o.id NOT IN ( SELECT a FROM
You don't use the VALUES keyword when inserting from a SELECT statement.
VALUES
SELECT
INSERT INTO t2 (a, b) SELECT a, b FROM `t1` AS o WHERE o.id NOT IN ( SELECT a FROM t2 )