oracle的drop table if exists

利用存储实现 
create or replace procedure proc_dropifexists( 
    p_table in varchar2 
) is 
    v_count number(10); 
begin 
   select count(*) 
   into v_count 
   from user_tables 
   where table_name = upper(p_table); 

   if v_count > 0 then 
      execute immediate 'drop table ' || p_table ||' purge'; 
   end if; 
end proc_dropifexists; 


exec proc_dropifexists('d_product'); 
CREATE TABLE d_product ( 
  id number(12)  primary key, 
  product_name varchar(100) NOT NULL, 
  description varchar(100) default NULL, 
  add_time number(20) default NULL, 
  fixed_price number(38) NOT NULL, 
  dang_price number(38) NOT NULL, 
  keywords varchar(200) default NULL, 
  has_deleted integer default '0' NOT NULL , 
  product_pic varchar(200) default NULL 
  ) ;