PHP新手上路(11)

　　数据库链接

　　10. PHP最大的特色就是操作数据库的能力特别的强大，PHP提供对多种数据库的支持。

　　通过PHP你可以轻松的连接到数据库，请求数据并将其显示在你的web站点中，甚至修改数据库中的数据。在这一节里我们主要以在互联网上跟PHP一起使用得最多的MySQL数据库为例，介绍一下相关的MySQL数据库的操作函数以及数据库的基本操作等方面的知识。

　　在MySQL数据库中，我们用来连接数据库的函数有两个，它们分别为：

integer mysql_connect(string host,string user,string password);integer mysql_pconnect(string host,string user,string password);

　　mysql_connect函数和mysql_pconnect函数都是对指定主机上MySQL数据库的连接，如果该数据库位于一个不同的端口，则可以在主机名后加上冒号和端口号。函数的参数也可以缺省不填，如果不填参数，默认的主机名是localhost，用户名为数据库管理员，默认值为root，密码为空。与数据库连接成功之后，这两个函数都可以返回一个连接号，如果连接失败，则返回一个false值。让我们来看看下面几句语句：

？$db=mysql_connect("localhost","user","password");mysql_select_db("mydb",$db);？

　　注释：

　　$db=mysql_connect("localhost","user","password"); 我们将mysql的链接参数，包括主机名、用户名和密码作为mysql_connect()的参数，同时得到返回值为$db，这样，在下面的语句中，我们就可以将变量$db作为一个连接mysql数据库的连接号来使用。

　　mysql_select_db("mydb",$db); 将PHP程序链接到mydb数据库中，这样程序与数据库的链接就完成了。

　　10.1 一个简易的数据库留言簿

　　在完成数据库的链接之后，我们就可以对数据库进行一系列的操作。下面是一个简易的数据库留言簿程序（guestbook.php3）：

　　我假设你机子上的MySQL数据库以及管理MYSQL数据库的工具 Phpmyadmin_2. 0.5都已经安装完成，并且可以正常工作。

　　我们要做的第一件事情是创建一个留言数据库，假定名字为： mydb。

　　1、启动浏览器，打开Phpmyadmin_2. 0.5 的管理WEB界面。

　　2、在Create new database文本框内输入数据库名称mydb，然后按create按键。

　　下一步，我们要在该留言数据库下创建一个数据表，假定名字为： guestbook。

　　创建该数据表的命令如下所示：

CREATE TABLE guestbook (ID INT NOT NULL AUTO_INCREMENT, name CHAR(250), email CHAR(250), job CHAR(250), comments BLOB, PRIMARY KEY(ID));

　　最后，将下面的留言簿程序挎贝到你机子的可写目录下面，并保存成guestbook.php3文件。就这么简单，你已经有了自己的留言簿了。

　　10.2 留言簿程序（guestbook.php3）：

？php/* $host : your MySQL-host, usually 'localhost' *//* $user : your MYSQL-username *//* $password : your MySQL-password *//* $database : your MySQL-database *//* $table : your MySQL-table *//* $page_title : the title of your guestbook-pages *//* $admin_mail : email-address of the administrator to send the new entries to *//* $admin_name : the name of the administrator *//* $html_mail : say yes if your mail-agent can handle HTML-mail, else say no */$host = "localhost";$user = "";$password = "";$database = "mydb";$table = "guestbook";$page_title = "pert guestbook";$admin_mail = "pert@21cn.com";$admin_name = "Webmaster";$html_mail = "no";？HTMLHEADTITLE？php echo $page_title; ？/TITLE/HEADBODY BGCOLOR="#FFFFFF" LINK="#000000"FONT FACE="Verdana" SIZE="-2"？/* connect to the database */mysql_pconnect("$host","$user","$password") or die("Can't connect to the SQL-server");mysql_select_db("$database");/* action=view : retrieve data from the database and show it to the user */if($action == "view") {/* function for showing the data */function search_it($name) {/* some vars */global $offset,$total,$lpp,$dir;global $table,$html_mail,$admin_name,$admin_mail;/* select the data to get out of the database */$query = "SELECT name, email, job, comments FROM $table";$result = mysql_query($query);$total= mysql_numrows($result);print "CENTERFONT FACE="Verdana" SIZE="-2"A HREF="guestbook.php3？action=add" onMouseOver="window.status='Add your name';return true" onMouseOut="window.status='';return true" TITLE="Add your name"加入留言/A/FONT/CENTERbrbr";if ($total== 0) {print "CENTER此刻没人留言/CENTERbrbr"; }elseif ($total 0) {/* default */$counter=0;if ($dir=="") $dir="Next";$lpp=5;if ($offset==0) $offset=0;if ($dir=="Next") {if ($total  $lpp) {$counter=$offset;$offset+=$lpp;$num=$offset;if ($num  $total) {$num=$total; } }else {$num=$total; } }elseif ($dir=="Previous") {if ($total  $lpp) {$offset-=$lpp;if ($offset  0) {$offset=0; }$counter=$offset-$lpp;if ($counter  0)$counter=0;$num=$counter+$lpp; }else {$num=$total; } }while ($counter  $num) {$j=0;$j=$counter + 1;/* now really grab the data */$i1=mysql_result($result,$counter,"name");$i2=mysql_result($result,$counter,"email");$i3=mysql_result($result,$counter,"job");$i4=mysql_result($result,$counter,"comments");$i4 = stripslashes ("$i4");/* print it in a nice layout */print "CENTERn";print "TABLE WIDTH=400 BORDER=0 ALIGN=CENTER VALIGN=TOPTRTDFONT FACE="Verdana" SIZE="-2"n";print "HRn";print "BRBName:/B $i1n";print "BRBemail:/BA HREF="mailto:$i2" onMouseOver="window.status='Email $i2';return true" onMouseOut="window.status='';return true" TITLE="Email $i2"$i2/An";print "BRBJob:/B $i3n";print "BRBComment:/Bn";print "BR$i4n";print "/FONT/TD/TR/TABLEn";print "/CENTERn";$counter++;}}mysql_close();}/* execute the function */search_it($name);/* See if we need to put on the NEXT or PREVIOUS buttons */if ($total  $lpp) {echo("form action="$PHP_SCRIPT" method="POST"n");/* See if we need a PREVIOUS button */if ($offset  $lpp) {echo("input type="submit" value="Previous" name=dirn"); }/* See if we need a NEXT button */if ($offset  $total) {echo("input type="submit" value="Next" name=dirn"); }echo("input type=hidden name="offset" value="$offset"n");echo("input type=hidden name="name" value="$name"n");echo("/form");}}/* action=add : show a form where the user can enter data to add to the database */elseif($action == "add") { ？TABLE WIDTH="460" ALIGN="CENTER" VALIGN="TOP"TH COLSPAN="2"P请您填写留言/THFORM NAME="guestbook" ACTION="guestbook.php3？action=send" METHOD="POST"TRTD ALIGN="RIGHT" VALIGN="TOP"您的大名:/TDTDINPUT TYPE=text NAME=name/TD/TRTRTD ALIGN="RIGHT" VALIGN="TOP"您的E-mail:/TDTDINPUT TYPE=text NAME=email/TD/TRTRTD ALIGN="RIGHT" VALIGN="TOP"您的工作:/TDTDINPUT TYPE=text NAME=job/TD/TRTRTD ALIGN="RIGHT" VALIGN="TOP"您的留言:/TDTDTEXTAREA NAME=comments COLS=40 ROWS=6/TEXTAREAPINPUT TYPE=submit VALUE=Submit INPUT TYPE=Reset VALUE=ResetA ALIGN="RIGHT" HREF="guestbook.php3？action=view" onMouseOver="window.status='Read all comments first';return true" onMouseOut="window.status='';return true" TITLE="Read all comments first"FONT SIZE="-2"先观看所有的留言/FONT/A/TD/TR/FORM/TABLE/CENTER？}/* action=send : add the data from the user into the database */elseif($action == "send") {/* check if a HTML-mail should be send or a plain/text mail */if($html_mail == "yes") {mail("$admin_name $admin_mail","PHP3 Guestbook Addition","HTMLBODYFONT FACE="Century Gothic"TABLE BORDER="0" WIDTH="100%" CELLSPACING="4"TR$name ($email) schreef het volgende bericht in het gastenboek :/TRTRTD ALIGN="LEFT" /TDTD ALIGN="LEFT" NOWRAP /TD/TRTRTD ALIGN="LEFT"$comments/TDTD ALIGN="LEFT" NOWRAP /TD/TRTRTD ALIGN="LEFT" /TDTD ALIGN="LEFT" NOWRAP /TD/TRTRTD ALIGN="LEFT"您的留言:/TDTD ALIGN="LEFT" NOWRAP$name/TD/TRTRTD ALIGN="LEFT"您的大名:/TDTD ALIGN="LEFT" NOWRAP$email/TD/TRTRTD ALIGN="LEFT"您的email:/TDTD ALIGN="LEFT" NOWRAP$job/TD/TRTRTD ALIGN="LEFT"您的工作:/TD/TR/TABLE/BODY/FONT/HTML", "From: $name $emailnReply-To: $name $emailnContent-type: text/htmlnX-Mailer: PHP/" . phpversion());}/* MySQL really hates it when you try to put things with ' or " characters into a database, so strip these...*/$comments = addslashes ("$comments");$query = "INSERT INTO guestbook VALUES('','$name', '$email', '$job', '$comments')";$result = MYSQL_QUERY($query);？BRP ALIGN = CENTER感谢, ？php echo $name; ？, 您的留言.BRP ALIGN = CENTERA HREF="guestbook.php3？action=view" onMouseOver="window.status='View your comment now';return true" onMouseOut="window.status='';return true" TITLE="View your comment now"观看留言/ABRBR？}/* if there's no action given, then we must show the main page */else {/* get the number of entries written into the guestbook*/$query = "SELECT name from guestbook";$result = MYSQL_QUERY($query);$number = MYSQL_NUMROWS($result);if ($number == "") {$entry = "还没有人留过言"; }elseif ($number == "1") {$entry = "目前留言人数1人"; }else {$entry = "目前留言人数 $number 人"; }echo "CENTERBR";echo "P$entryBR";echo "H4FONT FACE="Verdana" SIZE="3"A HREF="guestbook.php3？action=add" onMouseOver="window.status='请您留言';return true" onMouseOut="window.status='';return true" TITLE="Add your name to our guestbook"请您留言/A/FONT/H4";if ($number  "") {echo "H4FONT FACE="Verdana" SIZE="3"A HREF="guestbook.php3？action=view" onMouseOver="window.status='观看留言';return true" onMouseOut="window.status='';return true" TITLE="View the names in our guestbook"观看留言/A/FONT/H4"; }echo "/P/CENTER";}？BRSMALLCENTER版权所有：A HREF="http://personal.668.cc/haitang/index.htm" onMouseOver="window.status='pert';return true" onMouseOut="window.status='';return true" TITLE="pert"无边天际/A/CENTER/SMALL/FONT/BODY/HTML