2018-09-04

第二天上课，还是觉得没什么好听的，虽然好像不会emmm，但是上课是真的无聊。
课是少的可怜，平均一天两节课。第一节是编译原理，第二节是 Database System。
第一节课让我想想讲了啥，没看课件，我也不知道emmm。我唯一记得老师说北航的计算机学生的要求，学习完数字电路和计算机组成原理需要自己做一个CPU，有自己的指令系统，然后学习完OS，需要自己做一个OS，跑在CPU上，学完编译原理，在OS上做一个编译器，写一个简单的程序，跑起来。大概有30%的学生完成。
听完，嗯？？？？？放到我们学校，也就3%吧？？？？？我现在都懂了啥emmmmm。
得了，拉倒吧。
the second class is Database System. Because this course request English when we study. OK, who cares.
I have learn something about databese in summer vacation. The class is also boring. I tihnk the process may be solwly for me.We have three part that will be studyed. The first part is many concept about database.Studying how to use SQL is the second part. The last part is to unstander why we should do in this way.
part 1: I should know what is database processing. OK, to be honest, I don’t know until I write this blog. I think it doesn’t matter. The most important is to know what is the nature and characteristics of databases. And we will learn the personal database system and the enterprise-class database system.
For a interrupt, teacher said metadata. what is the metadata. It is data about data. More specifically it describe data. For example. the property, resource search, history and so on.
OK, we go on. We should understand database design through three aspect existing data, new systems development, database redesign.
And then the characteristics of database.

• The purpose of a database is to help people keep track of things.
• A relational database stores data in tables. The tables has rows and columns, like those in a spreadsheet.
• Data are recorded facts and numbers.
• A database usually has multiple tables. Each table contains data about a different type of thing.
• Each row records the data for a specific instance.
• Each column of a table stores a characteristic common to all rows. Columns are also konwn as fields.
• Each row in a table is uniquely identified by a primary key. And the primary key is used to create relationships to other tables.

There are so many notes should be remembered. Of course, I don’t recite them at all. I will review them before the final exam. Yeah.

应该差不多了，老师都不给PPT，说是之前的学生拿PPT做了很坏的事情，嗯？？？？算了，大不了，一张张拍嘛，多大点事。
溜了溜了，最近感觉全身都累，莫名的。承受不住开学的现实吗，怎么可能。

每日一句：我都不知道自己曾经这样，毫无指望地喜欢过你。