[练习] 【2018-4-9】每天进步一点点

DBMS is able to access and retrieve data from nonkey record fields. That is, the DBMS is able to structure and tie together the logically related data from several large files.
Logical Structures. Identifying these logical relationships is a job of the data administrator. A data definition language is used for this purpose. The DBMS may then employ one of the following logical structuring techniques during storage access, and retrieval operations [1]:

DBMS可综合几个文件的数据项以回答用户对信息的查询，这就意味着DBMS能够访问和检索非关键记录字段的数据，即DBMS能够将几个大文件中逻辑相关的数据组织并连接在一起。
逻辑结构。确定这些逻辑关系是数据管理者的任务，由数据定义语言完成。DBMS在存储、访问和检索操作过程中可选用以下逻辑构造技术:

The Eggs
After they cut down the sycamore tree, it seemed like everything else fell apart, too. Champ died. And then I found out about the eggs. It was
Champ's time to go, and even though I still miss him, I think it's been easier for me to deal with his death than it has been for me to deal with the truth about the eggs. I still cannot believe it about the eggs.
The eggs came before the chickens in our case, but the dog came before them both. One night when I was about six years old, Dad came home
from work with a full-grown dog tied down in the back of his truck. Someone had hit it in the middle of an intersection, and Dad had stopped to see
how badly it was hurt. Then he noticed that the poor thing was skinny as a rail and didn't have any tags. “Starving and completely disoriented,” he
told my mother. “Can you imagine someone abandoning their dog like that?”

鸡蛋无花果树被砍倒以后，似乎一切都分崩离析了。冠军死了。然后我发现关于鸡蛋的真相。冠军到了该离开的时候，虽然我很想它，但是对我来说，接受冠军的离去比接受鸡蛋的真相还要来的容易些。我仍然不敢相信鸡蛋的事。
在这个事件中，鸡蛋比鸡来得更早，而狗要来的比它们两个都早。我六岁的时候，爸爸下班回来，卡车厢里栓着一只已经完全长大的狗。有人在十字路口中间打它，爸爸停下来查看它的伤势。他发现这个可怜的小东西瘦得像根铁轨，没有任何证明身份的东西。“它饿极了，完全迷了路。”他告诉我妈妈。“你能想象有人这样抛弃他们的狗吗？”