Create Sequence Through Trigger

CREATE OR REPLACE TRIGGER my_trigger
BEFORE INSERT
ON qname
FOR EACH ROW
-- Optionally restrict this trigger to fire only when really needed
WHEN (new.qname_id is null)
DECLARE  v_id qname.qname_id%TYPE;
BEGIN
-- Select a new value from the sequence into a local variable. As David
-- commented, this step is optional. You can directly select into :new.qname_id SELECT qname_id_seq.nextval INTO v_id FROM DUAL;
-- :new references the record that you are about to insert into qname. Hence,
-- you can overwrite the value of :new.qname_id (qname.qname_id) with the value
-- obtained from your sequence, before inserting :new.qname_id := v_id;END my_trigger;