pub(pub_code char(2),pub_name varchar2(32))
book(book_code char(8),book_name varhcar2(128),pub_code char92),author_code
char(4),book_mem varchar2(128))
author(author_code char(4),author_name varchar2(10),sex char(1), age
number(3),dir varchar2(64))
auth_list(auth_date date,author_code char(4))
在PL/SQL中有以下两种字义
v_book_row book%rowtype;
v_book_code book.bank_code%type;
请说明v_book_row,v_book_code变量的含义以及数据类型
参考答案