First build a sequence, then build a trigger implementation!
CATA0 is a table name, and cata0_id is a field that needs to increase!
Create sequence seq_cata0
INCREMENT BY 1
START WITH 1
MaxValue 9999999
/
Create Trigger TRG_CATA0 BEFORE
INSERT on cata0
For Each Row Begin
SELECT SEQ_CATA0.NEXTVAL
INTO: New.cata0_id
From Dual;
END TRG_CATA0;
