请教一个oracle存储问题

Question

create or replace
procedure change_tel_number
as
telephone_number varchar2(8):='5565655';
begin
  if substr(telephone_number,1,1)='2' then
    telephone_number:='5'||telephone_number;
  else
    telephone_number:='6'||telephone_number;
  end if;
end;

Answer 1

使用DECODE函数SELECT decode(substr(telephone_number,1,1),'2','5'||telephone_number,'6'||telephone_number) FROM dual;