从一个不错的留言本弄的mysql数据库操作类

<?php class mysql{   var $querynum = 0;   function connect($dbhost, $dbuser, $dbpw, $dbname = '',$dbcharset='') {     if(!@mysql_connect($dbhost, $dbuser, $dbpw)) {       $this->show('Can not connect to MySQL server');       return false;     }     if($dbname) {       $this->select_db($dbname);     }     if($this->version() > '4.1' && $dbcharset) {       $this->query("SET NAMES '".$dbcharset."'");     }     return true;   }   function select_db($dbname) {     return mysql_select_db($dbname);   }   function fetch_array($query, $result_type = MYSQL_ASSOC) {     return @mysql_fetch_array($query, $result_type);   }   function query($sql, $type = '') {     if(!($query = mysql_query($sql))) $this->show('MySQL Query Error', $sql);     $this->querynum++;     return $query;   }   function affected_rows() {     return mysql_affected_rows();   }   function result($query, $row) {     return mysql_result($query, $row);   }   function num_rows($query) {     return @mysql_num_rows($query);   }   function num_fields($query) {     return mysql_num_fields($query);   }   function free_result($query) {     return mysql_free_result($query);   }   function insert_id() {     return mysql_insert_id();   }   function fetch_row($query) {     return mysql_fetch_row($query);   }   function version() {     return mysql_get_server_info();   }   function close() {     return mysql_close();   }   function error() {     return mysql_error();   }   function show($message = '', $sql = '') {     if(!$sql) echo $message;     else echo $message.'<br>'.$sql.'<br>'.$this->error();   } } class page extends mysql{   function pagination($sql,$maxnum,$page,$maxpages,$pagepre,$ext=''){     global $sum,$stail,$link,$lmid,$ltail,$curpage;//$ext='&class=3'     $SELF = $_SERVER['PHP_SELF'];     $query = $this->query($sql);     $rows = $this->fetch_array($query,MYSQL_NUM);     $totalrows = $rows[0];     $totalpages = ceil($totalrows/$maxnum);     $startnum = ($page - 1)*$maxnum;     $string = $sum.$totalrows.$stail.$sum.$page."/".$totalpages.$stail;     if($page != 1){       $string .= $link.$SELF."?page=1".$ext.$lmid."|&lsaquo;".$ltail;       $string .= $link.$SELF.'?page='.($page - 1).$ext.$lmid."&lsaquo;&lsaquo;".$ltail;     }     if($maxpages>=$totalpages){       $pgstart = 1;$pgend = $totalpages;     }     elseif(($page-$pagepre-1+$maxpages)>$totalpages){       $pgstart = $totalpages - $maxpages + 1;       $pgend = $totalpages;     }     else{       $pgstart=(($page<=$pagepre)?1:($page-$pagepre));       $pgend=(($pgstart==1)?$maxpages:($pgstart+$maxpages-1));     }     for($pg=$pgstart;$pg<=$pgend;$pg++){       if($pg == $page){         $string .= $curpage.$SELF."?page=".$pg.$ext.$lmid.$pg.$ltail;       }       else $string .= $link.$SELF."?page=".$pg.$ext.$lmid.$pg.$ltail;     }     if($page != $totalpages){       $string .= $link.$SELF.'?page='.($page + 1).$ext.$lmid."&rsaquo;&rsaquo;".$ltail;       $string .= $link.$SELF.'?page='.$totalpages.$ext.$lmid."&rsaquo;|".$ltail;     }     return $string;   } } function html($str,$allowhtml=0){   $str = get_magic_quotes_gpc()?$str:addslashes($str);   if(!$allowhtml){$str = htmlspecialchars($str);}   return $str; } function dehtml($str,$allowhtml=0){   $str = stripslashes($str);   if(!$allowhtml){$str = nl2br($str);}   return $str; } function deip($str){   $arr = explode('.',$str);   $str = $arr[0].'.'.$arr[1].'.'.$arr[2].'.*';   return $str; } function setting($login=false){   global $db,$mydbpre;   if($login) $sql = "select * from {$mydbpre}setting";   else $sql = "select * from {$mydbpre}setting where keyword != 'username' and keyword != 'password'";   $query = $db->query($sql);   while($row = $db->fetch_array($query)){     $arr[$row['keyword']] = $row['val'];     if($row['keyword'] == 'name') $arr['title'] = $row['val'].' - Powered by PHPfans';   }   return $arr; } function checkcontent($content){   global $db,$mydbpre,$mearr;   $arrword = $arrip = array();   $sql = "select * from {$mydbpre}ban where b_type != 0";   $query = $db->query($sql);   while($row = $db->fetch_array($query)){     if($row['b_type'] == 1) $arrword[] = $row['b_val'];     elseif($row['b_type'] == 2) $arrip[] = $row['b_reval'];   }   foreach($arrip as $value){     $value = preg_quote($value,'/');     $value = str_replace('/*','/d{1,3}',$value);     if(preg_match('/^('.$value.')$/',$_SERVER['REMOTE_ADDR'])){       showmessage($mearr[8],'index.php');     }   }   foreach($arrword as $val){     $val = preg_quote($val,'/');     if(preg_match('/'.$val.'/',$content)){       showmessage($mearr[7],'index.php');     }   } } function replaceword($content){   global $db,$mydbpre;   $sql = "select * from {$mydbpre}ban where b_type = 0";   $query = $db->query($sql);   while($row = $db->fetch_array($query)){     $content = str_replace($row['b_val'],$row['b_reval'],$content);   }   return $content; } function showadmin($message,$referer=''){   $str = '';   if($referer != '') $str .= '<meta http-equiv="refresh" content="2;URL='.$referer.'" />';   $str .= '  <table width="45%" align="center" style="border:1px solid #eeeeee; margin-top:50px;">  <tr bgcolor="#CCCCCC">   <td height="25">信息提示</td>  </tr>  <tr align="center">   <td style="padding:10px 0 10px 0">'.$message;   if($referer != '') $str .= '<br />  <br />  <a href="'.$referer.'">如果你的页面没有跳转,请点这里</a>';   $str .= '  </td>  </tr>  </table>';   echo $str;   exit; } function showmessage($message,$referer=''){   global $setting,$db;   $start = gettime();   echo <<<EOT <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=gbk" /> <title>php爱好者留言簿_提示信息</title> <link type="text/css" href="guest.css" rel="stylesheet"> EOT;   if($referer != '') echo '<meta http-equiv="Refresh" content="2;URL='.$referer.'" />';   echo <<<EOT </head> <body> <center> EOT;   require_once('header.html');   echo <<<EOT <div class="message"> <h1>php爱好者留言簿 提示信息</h1> {$message} EOT;   if($referer != ''){     echo <<<EOT <br /> <a href="{$referer}">如果您的浏览器没有自动跳转，请点击这里</a> </div> EOT; } require_once('footer.html'); echo <<<EOT </center> </body> </html> EOT; exit; } function gettime() {   $t = explode(" ",microtime());   return $t[1] + $t[0]; } function checklogin($exit=true){   if(!isset($_COOKIE['islogin']) || $_COOKIE['islogin'] != 1){     if($exit) {       echo "请先登陆，谢谢。";       exit;     }   }   else setcookie('islogin',1,time()+60*20); } ?>