SQL Workshop - Beginning Oracle Application Express 4.2 - page 55

create or replace trigger "BI_TICKETS"
before insert on "TICKETS"
for each row
begin
if :NEW."TICKET_ID" is null then
select "TICKETS_SEQ".nextval into
:NEW."TICKET_ID" from sys.dual;
end if;
end;

Now that you have the TICKETS table defined, let's go back and create
the TICKET_DETAILS table. This time you'll create a foreign key to the
TICKETS table, as a CASCADE DELETE . This means that if you delete a
ticket, the ticket details will automatically be deleted as well.

10. Start the Create Table Wizard using the Create button.

11. Enter the table name and column definitions based on the ERD and Figure

4-6 , and click Next .

Figure 4-6. Defining the TICKET_DETAILS table

The next set of steps is purposefully a bit more vague than the previous
ones. You should be used to using the Create Table Wizard by now, but if
you need a refresher, just look at the previous steps.