Web Building Learning Notes (0)--basic concept understanding and resource learning (copy from W3school)

Last Update:2015-04-14 Source: Internet

Author: User

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I. Study 1, WWW-World Wide Web what is WWW?

www (World Wide web)
The World Wide Web is often referred to as
The web is a network of computers all over the world
All computers in the WEB can communicate with each other
All of these computers use a communication standard called HTTP

How does WWW work?

Web information is stored in a document called a Web page
A Web page is stored on a computer called a Web server
The computer that reads the Web page is called the Web client
Web client to view Web pages through a program called a browser
The main browsers have Internet Explorer and Mozilla Firefox

How does the browser read the page?

A browser can read a Web page on a server with a single request
A request is a standard HTTP request that contains a page address
The page address looks like this: http://www.someone.com/page.htm

How does the browser display the page?

All pages contain the structure of how they are displayed
browsers display pages by reading these structures
The most common display structure is called HTML tags
HTML tags for paragraphs are like this:
Define the paragraph in HTML like this: this is a paragraph

WHO develops web standards?

Web standards are not developed by Netscape or Microsoft
The web's rule-making body is the
The World Wide Web Consortium refers to www Wide Consortium
A wide range of specifications into web standards
The most core Web standards are HTML, CSS, XML
The latest HTML standard is XHTML 1.0

Tutorial: http://www.w3school.com.cn/w3c/index.asp

2, HTML first knowledge of what is HTML?

HTML is a language used to describe a Web page.

HTML refers to Hypertext Markup Language (Hyper Text Markup Language)
HTML is not a programming language, but a markup language (Markup language)
Markup language is a set of tag tags (markup tag)
HTML uses tag tags to describe web pages

HTML tags

HTML tag tags are often referred to as HTML tags (html tag).

HTML tags are keywords surrounded by angle brackets , such as
HTML tags are usually paired up , such as and
The first label in the pair is the start tag , the second is the end tag
Start and end tags are also known as open tags and closed labels

HTML document = Web page

HTML Document Description Web page
HTML documents contain HTML tags and plain text
HTML documents are also called Web pages

The purpose of a Web browser is to read HTML documents and display them as Web pages. Instead of displaying HTML tags, the browser uses tags to interpret the contents of the page:

 <  html  >  <  body  >  <  h1  >  My first Heading</ h1  >  <  p  >  My first paragraph. </ p  >  </ body  >  </ html  >

Example explanation

Text description page between
The text between <body> and </body> is visible in the page content
The text between
Text between and is displayed as a paragraph

3, the first knowledge of CSS

CSS Overview

CSS refers to cascading style sheets (Cascading style sheets)

Style defines how HTML elements are displayed
Styles are typically stored in style sheets
Add a style to HTML 4.0 to solve the problem of separating content from performance
external style sheets can greatly improve productivity
External style sheets are typically stored in CSS files
Multiple style definitions can Cascade to a

The style solves a common problem

HTML tags were originally designed to define document content. by using

Because the two main browsers (Netscape and Internet Explorer) constantly add new HTML tags and attributes (such as font labels and color attributes) to the HTML specification, it becomes increasingly difficult to create a site that is clearly independent of the document's presentation layer.

To solve this problem, the World Wide Web Consortium, a non-profit standardization consortium, is tasked with the standardization of HTML and Creating styles (styles) beyond HTML 4.0.

Cascading style sheets are supported by all major browsers.

Style sheets greatly increase productivity

Style sheets define how HTML elements are displayed, and font labels and color properties in styles such as HTML 3.2 are usually saved in an external. css file. By simply editing a simple CSS document, an external style sheet gives you the ability to change the appearance of all page layouts in your site at the same time.

CSS can be called a breakthrough in WEB design because it allows you to control the style and layout of multiple pages at the same time. As a web developer, you can define a style for each HTML element and apply it to as many pages as you want. To make a global transformation, you simply change the style, and all elements in the site are automatically updated.

Multiple styles are stacked as one

Style sheets allow style information to be specified in several ways. Styles can be defined in a single HTML element, in the header element of an HTML page, or in an external CSS file. You can even reference multiple external style sheets within a single HTML document.

Stacking order

What style is used when the same HTML element is defined by more than one style?

Generally, all styles are stacked in a new virtual style sheet according to the following rules, where the number 4 has the highest precedence.

Browser default settings
External style sheet
Internal style sheet (inside the
Inline style (inside HTML elements)

Therefore, the inline style (inside the HTML element) has the highest precedence, which means that it will take precedence over the style declarations in the:

4, JavaScript first knowledge of what is JavaScript?

JavaScript is designed to add interactive behavior to HTML pages.
JavaScript is a scripting language (the scripting language is a lightweight programming language).
JavaScript consists of several lines of executable computer code.
JavaScript is usually embedded directly into an HTML page.
JavaScript is an explanatory language (that is, code execution is not precompiled).
All people can use JavaScript without buying a license

is Java and JavaScript the same?

Different!

In terms of concept and design, Java and JavaScript are two completely different languages.

Java (developed by Solar Micro systems) is a powerful and more complex programming language, like the same level of C and C + +.

5. What is XML in the first knowledge of XML?

XML refers to Extensible Markup Language (extensible Markup Language)
XML is a markup language , much like HTML
XML is designed to describe data
XML tags are not predefined. You need to define your own labels .
XML uses a file type declaration (DTD) or XML Schema to describe the data.
XML with a DTD or XML Schema is designed to be self-descriptive .
XML is a standard

XML is a standard

The Extensible Markup Language was established as a standard on February 10, 1998.

The main differences between XML and HTML

XML is designed to carry data.

XML is not intended to replace HTML.

XML and HTML are designed for different purposes:

XML is designed to describe data, and its focus is on the content of the data.

HTML is designed to display data with the focus on the appearance of the data.

HTML is designed to display information, while XML is intended to describe information.

XML without any behavior

XML is not a function of.

Maybe it's a little hard to understand, but XML doesn't do anything. XML is designed to structure, store, and transmit information.

Here is John's note to George, stored as XML:

<note><to>George</to><from>John</from>

This tag has a title and a message. It also contains information about the sender and the recipient. However, this XML document still doesn't do anything. It's just pure information wrapped in an XML tag. We need to write software or programs to transmit, receive, and display this document.

XML is free and extensible.

XML tags are not predefined. You must "invent" your own label.

Tags that are used to mark an HTML document and its structure are predefined. The creator of an HTML document can only use those tags that are defined in the HTML standard (such as ,

XML allows authors to define their own tags and their own document structure.

The tags in the example above are not defined in any of the XML standards. These tags are invented by the author of the XML document.

XML is a complement to HTML

XML is not a substitute for HTML.

It is important to understand that XML is not a substitute for HTML. In future WEB development, the most likely scenario is that XML is used to describe the data, and HTML is used to format and display the data.

Our best description of XML is that XML is a cross-platform, software-and hardware-independent tool for transmitting information.

The role that XML plays in future WEB development

XML will be ubiquitous.

When we see the rapid development of XML standards and the rapid pace at which a large number of software developers adopt this standard, it is really amazing.

We firmly believe that the role of XML in the future of the web will not renmin the HTML that has always been the cornerstone of the Web, and that XML will be the most common tool for all data processing and transmission.

6, server-side script first knowledge of what is server script?

Typically, the server returns this file when the browser requests an HTML file, but if the file contains a server-side script, the script in the HTML file is executed first before the HTML file is returned as plain HTML.

What can server scripts do?

Dynamically edit, change, or add any content to a Web page
Responding to user requests or data submitted by an HTML form
accessing data or databases and returning results to the browser
Customize pages for different users
Improve Web page security so that your Web page code will not be looked up through the browser

Important: Because the script executes on the server, the browser can display server-side files without scripting support!

ASP and PHP

You can't view the source code to see the ASP or PHP source code, you see only the output from the server, those pure HTML. This is because the script has been executed on the server before the result is sent to the browser in pure HTML.

ASP instance

Http://www.w3school.com.cn/tiy/s.asp?f=demo_aspe_text

Http://www.w3school.com.cn/tiy/s.asp?f=demo_aspe_formatting

7. SQL Primary Knowledge

SQL is the standard computer language for accessing and working with databases.

Managing Data with SQL

Structured Query Language (SQL) is the standard language for accessing databases, including SQL Server, Oracle, MySQL, Sybase, and access, among others.

For those who want to store data in a database and get data from it, the knowledge of SQL is not worth measuring.

What is SQL?

SQL refers to Structured Query language (Structured Query Language)
SQL gives us the ability to access a database
SQL is an ANSI standard computer language
SQL database-oriented query execution
SQL can retrieve data from the database
SQL can insert new records in the database
SQL to delete records from the database
SQL is easy to learn

SQL is a standard-but ...

SQL is an ANSI standard computer language used to access and manipulate database systems. SQL statements are used to retrieve and update data in the database. SQL can work with database programs, such as Ms Access, DB2, Informix, MS SQL Server, Oracle, Sybase, and other database systems.

Unfortunately, there are many different versions of the SQL language, but to be compatible with ANSI standards, they must collectively support some key keywords (such as SELECT, UPDATE, DELETE, INSERT, WHERE, and so on) in a similar way.

Note: In addition to the SQL standard, most SQL database programs have their own private extensions!

SQL Database Tables

A database typically contains one or more tables. Each table is identified by a name (for example, "customer" or "order"). The table contains records (rows) with data.

The following example is a table named "Persons":

The table above contains three records (one for each person) and four columns (last name, first name, address, and city).

SQL Query Program

With SQL, we can query a database and get a result set that is returned.

The query program looks like this:

SELECT LastName from Persons

The result set looks like this:

Note: Some database systems require semicolons to be used at the end of the SQL command. Semicolons are not used in our tutorials.

SQL Data Manipulation Language (DML)

SQL (Structured Query language) is the syntax for executing queries. However, the SQL language also contains syntax for updating, inserting, and deleting records.

These query and UPDATE statements come from the DML portion of SQL:

SELECT -get data from a database table
Update-updating data in a database table
Delete-deletes data from the database table
INSERT INTO-inserts data into a database table

SQL Data Definition language (DDL)

The Data Definition Language section of SQL gives us the ability to create or delete tables. We can also define indexes (keys), specify links between tables, and impose constraints between tables.

The most important DDL statement in SQL:

CREATE TABLE-Creates a new table
ALTER TABLE -Change (change) database table
Drop Table-delete tables
CREATE index-Creating indexes (search key)
Drop Index-delete indexes

Web Building Learning Notes (0)--basic concept understanding and resource learning (copy from W3school)

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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