一. 字段 1. 添加 alter table book add column book_id varchar not null, book_title varchar(10) default ''; 2. 删除 alter table book drop book_id, book_title;// 外键时alter table book drop book_id, book_tit
一. 字段 1. 添加 alter table book add column book_id varchar not null, book_title varchar(10) default ''; 2. 删除 alter table book drop book_id, book_title;// 外键时alter table book drop book_id, book_tit