I call $wpdb->query() on a query like

INSERT INTO wp_ctt_timetables (name, homework, tod, class, dow, lesson) VALUES ('', '', '', 3, 0, 0);
INSERT INTO wp_ctt_timetables (name, homework, tod, class, dow, lesson) VALUES ('', '', '', 3, 0, 1);
INSERT INTO wp_ctt_timetables (name, homework, tod, class, dow, lesson) VALUES ('', '', '', 3, 0, 2);
INSERT INTO wp_ctt_timetables (name, homework, tod, class, dow, lesson) VALUES ('', '', '', 3, 0, 3);
-- and so on

But it doesn’t work and says this to the error log:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘INSERT INTO wp_ctt_timetables (name, homework, tod, class, dow, lesson) VALUES (‘ at line 2