2012年10月31日
十、连接和视图
摘要： Join Expressionsselect * from student, takes where student.ID =takes.ID;=select * from student natural joi... 阅读全文
posted @ 2012-10-31 20:12 he_qiao_2010 阅读(148) 评论(0) 推荐(0)
九、数据库的修改
摘要： l Deletion oftuples from a given relation (删除元组) l Insertion ofnew tuples into a given relation (插入新的元组) l... 阅读全文
posted @ 2012-10-31 20:09 he_qiao_2010 阅读(100) 评论(0) 推荐(0)