📄 web_sql.asp
字号:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en-US" xml:lang="en-US" xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>SQL Primer</title>
<link rel="shortcut icon" href="../favicon.ico" type="image/x-icon" />
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<meta name="Keywords" content="xml,tutorial,html,dhtml,css,xsl,xhtml,javascript,asp,ado,vbscript,dom,sql,colors,soap,php,authoring,programming,training,learning,beginner's guide,primer,lessons,school,howto,reference,examples,samples,source code,tags,demos,tips,links,FAQ,tag list,forms,frames,color table,w3c,cascading style sheets,active server pages,dynamic html,internet,database,development,Web building,Webmaster,html guide" />
<meta name="Description" content="Free HTML XHTML CSS JavaScript DHTML XML DOM XSL XSLT RSS AJAX ASP ADO PHP SQL tutorials, references, examples for web building." />
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="cache-control" content="no-cache" />
<link rel="stylesheet" type="text/css" href="../stdtheme.css" />
<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "../../https@ssl./default.htm" : "../../www./default.htm");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
var pageTracker = _gat._getTracker("UA-3855518-1");
pageTracker._initData();
pageTracker._trackPageview();
</script>
</head>
<body>
<a name="top"></a>
<table cellpadding="0" cellspacing="0" width="100%" bgcolor="#808080">
<tr>
<td width="234" valign="top">
<a href="../default.htm"><img src="../images/w3default80.jpg" border="0" alt="W3Schools" /></a>
</td>
<th valign="middle" align="left" class="right">
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*txtimg*/
google_ad_slot = "5330033957";
google_ad_width = 728;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript" src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
<noscript>
<a href="../default.asp" target="_blank"><img src="../banners/w6.gif" border="0" alt="W3Schools" /></a>
</noscript>
<br /></th>
</tr>
</table>
<table style="margin-left:1px" width="800px" border="0" cellpadding="0" cellspacing="2">
<tr>
<td width="137" class="content" valign="top"><br />
<a class="left" href="../default.asp" target="_top">
<img src="../images/homeicon.gif" border="0" alt="home" /></a>
<a class="left" href="../default.asp" target="_top">
<b>HOME</b></a>
<br /><br />
<b>Web Primer</b><br />
<a class="left" target="_top" href="default.asp" >Web Primer</a><br />
<a class="left" target="_top" href="web_www.asp" >Web WWW</a><br />
<a class="left" target="_top" href="web_html.asp" >Web HTML</a><br />
<a class="left" target="_top" href="web_css.asp" >Web CSS</a><br />
<a class="left" target="_top" href="web_javascript.asp" >Web JavaScript</a><br />
<a class="left" target="_top" href="web_xml.asp" >Web XML</a><br />
<a class="left" target="_top" href="web_scripting.asp" >Web Scripting</a><br />
<a class="left" target="_top" href="web_sql.asp" style='font-weight:bold;'>Web SQL</a><br /><br />
<b>Selected Reading</b><br />
<a class="left" target="_top" href="../browsers/browsers_stats.asp">Web Statistics</a><br />
<a class="left" target="_top" href="../site/site_glossary.asp">Web Glossary</a><br />
<a class="left" target="_top" href="../hosting/default.asp">Web Hosting</a><br />
<a class="left" target="_top" href="../quality/default.asp">Web Quality</a><br /><br />
<a class="left" target="_top" href="../forum/default.asp">W3Schools Forum</a><br /><br />
<a class="left" target="_top" href="../about/about_helping.asp">Helping W3Schools</a><br /><br />
<script type="text/javascript"><!--
google_ad_client = "pub-3440800076797949";
/*LeftLinkUnit*/
google_ad_slot = "4854527104";
google_ad_width = 120;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript"
src="../../pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td>
<td valign="top">
<table style="border: 1px solid gray" width="100%" bgcolor="#FFFFFF" border="0" cellpadding="5" cellspacing="0">
<tr>
<td>
<h1>SQL Primer</h1>
<a href="web_scripting.asp"><img border="0" src="../images/btn_previous.gif" width="100" height="20" alt="Previous" /></a>
<a href="default.asp"><img border="0" src="../images/btn_next.gif" width="100" height="20" alt="Next" /></a>
<hr />
<table><tr>
<td width="120"><img src="pic_sql.gif" border="0" alt="SQL" width="94" height="77" /></td>
<td valign="top"><b>SQL is a standard computer language for accessing and manipulating databases.</b></td>
</tr></table>
<hr />
<h2>Managing Data with SQL</h2>
<p>The Structured Query Language (SQL) is the standard language for accessing databases such as
SQL Server, Oracle, MySQL, Sybase, and Access.</p>
<p>Knowledge of SQL is invaluable for anyone wanting to store or retrieve data
from a database.</p>
<hr />
<h2>What is SQL?</h2>
<ul>
<li>SQL stands for <b>S</b>tructured <b>Q</b>uery <b>L</b>anguage</li>
<li>SQL allows you to access a database</li>
<li>SQL is an ANSI standard computer language</li>
<li> SQL can execute queries against a database</li>
<li>SQL can retrieve data from a database</li>
<li>SQL can insert new records in a database</li>
<li>SQL can delete records from a database</li>
<li>SQL can update records in a database</li>
<li>SQL is easy to learn</li>
</ul>
<hr />
<h2>SQL is a Standard - BUT....</h2>
<p>SQL is an ANSI (American National Standards Institute) standard computer
language for accessing and manipulating database
systems. SQL statements are used to retrieve and update data in a database. SQL works with database programs like MS Access, DB2, Informix, MS SQL Server,
Oracle, Sybase, etc.</p>
<p>Unfortunately, there are many different versions of the SQL language, but to be in
compliance with the ANSI standard, they must support the same
major keywords in a similar manner (such as SELECT, UPDATE, DELETE, INSERT,
WHERE, and others).</p>
<p><b>Note:</b> Most of the SQL database programs also have their own
proprietary extensions in addition to the SQL standard!</p>
<hr />
<h2>SQL Database Tables</h2>
<p>A database most often contains one or more tables. Each table is identified
by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with
data.</p>
<p>Below is an example of a table called "Persons":</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table1">
<tr>
<th align="left">LastName</th>
<th align="left">FirstName</th>
<th align="left">Address</th>
<th align="left">City</th>
</tr>
<tr>
<td>Hansen</td>
<td>Ola</td>
<td>Timoteivn 10</td>
<td>Sandnes</td>
</tr>
<tr>
<td>Svendson</td>
<td>Tove</td>
<td>Borgvn 23</td>
<td>Sandnes</td>
</tr>
<tr>
<td>Pettersen</td>
<td>Kari</td>
<td>Storgt 20</td>
<td>Stavanger</td>
</tr>
</table>
<p>
The table above contains three records (one for each person) and four columns (LastName, FirstName, Address, and City).</p>
<hr />
<h2> SQL Queries
</h2>
<p>With SQL, we can query a database and have a result set returned.
</p>
<p>A query like this:
</p>
<table class="ex" cellspacing="0" border="1" width="50%" id="table2">
<tr>
<td><pre>SELECT LastName FROM Persons</pre></td>
</tr>
</table>
<p>Gives a result set like this:
</p>
<table class="ex" cellspacing="0" border="1" width="50%" id="table3">
<tr>
<th align="left">LastName</th>
</tr>
<tr>
<td>Hansen</td>
</tr>
<tr>
<td>Svendson</td>
</tr>
<tr>
<td>Pettersen</td>
</tr>
</table>
<p>
<b>Note</b>: Some database systems require a semicolon at the end of the SQL statement.
We don't use the semicolon in our tutorials.</p>
<hr />
<h2>SQL Data Manipulation Language (DML)</h2>
<p>SQL (Structured Query Language) is a syntax for executing queries. But the SQL
language also includes a syntax to update, insert, and delete
records.</p>
<p>These query and update commands together form the Data Manipulation Language (DML)
part of SQL:</p>
<ul>
<li><b>SELECT</b> - extracts data from a database table</li>
<li><b>UPDATE</b> - updates data in a database table</li>
<li><b>DELETE</b> - deletes data from a database table</li>
<li><b>INSERT INTO</b> - inserts new data into a database table</li>
</ul>
<hr />
<h2>SQL Data Definition Language (DDL)</h2>
<p>The Data Definition Language (DDL) part of SQL permits database tables to be
created or deleted. We can also define indexes (keys), specify links between tables,
and impose constraints between database tables.</p>
<p>
The most important DDL statements in SQL are: </p>
<ul>
<li><b>CREATE TABLE</b> - creates a new database table</li>
<li><b>ALTER TABLE </b>- alters (changes) a database table</li>
<li><b>DROP TABLE</b> - deletes a database table</li>
<li><b>CREATE INDEX</b> - creates an index (search key)</li>
<li><b>DROP INDEX</b> - deletes an index
</li>
</ul>
<hr />
<h2>SQL Tutorial</h2>
<p>Study our <a href="../sql/default.asp">Complete SQL tutorial</a></p>
<hr />
<a href="web_scripting.asp"><img border="0" src="../images/btn_previous.gif" width="100" height="20" alt="Previous" /></a>
<a href="default.asp"><img border="0" src="../images/btn_next.gif" width="100" height="20" alt="Next" /></a>
<br />
<hr />
<!-- **** SPOTLIGHTS 1 **** -->
<iframe src="../banners/aspallframe.asp" height="110" width="485"
marginwidth="0" marginheight="0" frameborder="0" scrolling="no">
Your browser does not support inline frames or is currently configured not to display inline frames.
</iframe>
<hr />
<!-- **** SPOTLIGHTS 2 **** -->
<h2><a target="_blank" href="../../www.altova.com/ref/@s=w3s_spotlight&q=xmlspy">
Altova⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -