神马品牌网怀念是用于逝去的人吗:专业英语翻译
来源：百度文库 编辑：神马品牌网 时间：2024/04/28 17:43:25
Poet
• Code
• First name
• Surname
• Age
• Address
• Telephone
This is the complete list of fields from the poet table
Subscriber view
• Code
• First_name
• Surname
• Grade
This view could be used to allow others to see the poet's code, name and surname, but not allow them access to personal information. Or, a view could be a combination of a number of tables, such as in this example:
Poet
• Code
• First name
• Surname
• Age
• Address
• Telephone
Poem
• Poem code
• Poet code
• Title
Subscriber view
• First_name
• Surname
• Poem title
Views are often used for security purposes. Junior developers may need access to certain portions of a table, but they do not need access to all the data. What they don't need, even if it is from the same table, is hidden and safe from manipulation or viewing. Also, views allow SQL queries to be much simpler. For example, without views, a developer may have to use the following query:
SELECT first_name, surname, poem FROM poet, poem
WHERE poem. poet_code=poet. code AND poet. title='Once';
With the view, a developer could do the same with:
SELECT first_name, surname, poem from subscriber_view;
Much more simple for a junior developer who hasn't yet learnt how to do joins across multiple tables, and less hassle for a senior developer too!
This has been a brief introduction to relational databases. Hopefully it's put some of the terms you've come across in context, and whetted your appetite to explore further.
1、 What does this article talk about?
A、cursor B、view C、key D、tuple
2、 Which is correct key word to create a view in the following four options?
A、create dataBase B、create table C、create view D、create cursor
3、 Which one is false in the following four sentence?
A、 Views are often used for security purposes.
B、 a view could be a combination of a number of tables
C、 Views are virtual tables.
D、 Views are databases.
4、A is a group of records.
A. field B. table C. database D. file
5、The point at which a column and a row intersects is called a/an .
A. cell B. pointer C. value D. label
视图是虚表，他们并不包含任何自己的数据，他们可以被认为是
允许我们访问数据或者是数据子集的一种结构。一张视图可以包括一
张表的子集，例如：
Poet
• Code
• First name
• Surname
• Age
• Address
• Telephone
以上是poet这张表的所有的字段的完整列表。
Subscriber view
• Code
• First_name
• Surname
• Grade
上面这个是张视图，这张视图被用于允许其他人访问poet那张表中的c
ode，name和surname字段，但是不允许他们访问其他私人信息。或者
，一张视图也可以是一些表的联合。例如：
Poet （poet表）
• Code
• First name
• Surname
• Age
• Address
• Telephone
Poem （poem表）
• Poem code
• Poet code
• Title
Subscriber view （视图）
• First_name
• Surname
• Poem title
视图通常被用作安全的目的。初级的开发者可能需要访问一张条的特
定部分，但是他们并不需要访问表的所有的数据。他们所不需要，及
时是来源于同一张表，就可以被隐藏起来，避免被操作或者是访问。同时，视图让sql查询语句变得更简单。举个例子来说，没有视图，开发人员可能必须使用下面的查询：
SELECT first_name, surname, poem FROM poet, poem
WHERE poem. poet_code=poet. code AND poet. title='Once';
使用了视图，开发人员可以通过下面的语句达到相同的效果：
SELECT first_name, surname, poem from subscriber_view;
对于一个还没有学习如何做多表连接的初级开发者来说，采用视图会更简单，同时也会让一个高级开发者减少跟其他人争辩的次数。
以上对关系数据库作了一个简要的介绍，希望你通过这篇文章可以从一些方面的了解，增加你想要更进一步的了解的欲望。
1、这篇文章讲述的是什么？
A、游标 B、视图 C、主键 D、元组
2、以下4个选项中那一个才是创建视图的正确的关键字？
A、create dataBase B、create table C、create view D、create
cursor
3、以下4句，哪一句是错误的？
A、 视图通常被用于安全的目的。
B、一张视图可以由多张表联合而成。
C、视图是虚表。
D、视图是数据库。
4、什么是一个记录集？
A、字段 B、表 C、数据库 D 、文件
5、行列的交叉点叫做____？
A. cell B. pointer C. value D. label