我正在尝试按照该指南创建pl/sql块，并且在上出现ORA-00922：missing或invalid选项SET orderNumberSEQ...。我究竟做错了什么？

declare
orderNumberSEQ number(5);
userid varchar(20);

begin
insert into bs_orders (userid, ono, timepurchased)
values('lilith', orderNum_seq.NEXTVAL,(SELECT current_timestamp FROM dual));

SET orderNumberSEQ := orderNum_seq.CURRVAL;

SELECT userid FROM bs_orders
where ono = orderNumberSEQ;
end;
/