drop database library_name; 删除库
drop table table_name; 删除表
drop user user_name; 删除用户
drop key name_uk on emp; 删除键
drop index emp_news_index on emp; 删除索引
drop database library_name; 删除库
drop table table_name; 删除表
drop user user_name; 删除用户
drop key name_uk on emp; 删除键
drop index emp_news_index on emp; 删除索引