<?php/******************************************* mysql-rw-php version 0.1 @ 2009-4-16*** code by hqlulu#Gmail.com*** http://www.aslibra.com*** http://code.google.com/p/mysql-rw-php/*** code modify from class_mysql.php (uchome)****************************************/class mysql_rw_php {  //查询个数  var $querynum = 0;  //当前操作的数据库连接  var $link = null;  //字符集  var $charset;  //当前数据库  var $cur_db = ”;  //是否存在有效的只读数据库连接  var $ro_exist = false;  //只读数据库连接  var $link_ro = null;  //读写数据库连接  var $link_rw = null;  function mysql_rw_php(){  }  function connect($dbhost, $dbuser, $dbpw, $dbname = ”, $pconnect = 0, $halt = TRUE) {    if($pconnect) {      if(!$this->link = @mysql_pconnect($dbhost, $dbuser, $dbpw)) {        $halt && $this->halt(’Can not connect to MySQL server’);      }    } else {      if(!$this->link = @mysql_connect($dbhost, $dbuser, $dbpw)) {        $halt && $this->halt(’Can not connect to MySQL server’);      }    }       //只读连接失败    if(!$this->link && !$halt) return false;       //未初始化rw时，第一个连接作为rw    if($this->link_rw == null)      $this->link_rw = $this->link;    if($this->version() > ‘4.1′) {      if($this->charset) {        @mysql_query(”SET character_set_connection=$this->charset, character_set_results=$this->charset, character_set_client=binary”, $this->link);      }      if($this->version() > ‘5.0.1′) {        @mysql_query(”SET sql_mode=””, $this->link);      }    }    if($dbname) {      $this->select_db($dbname);    }  }  //http://www.knowsky.com/php.asp 连接一个只读的mysql数据库  function connect_ro($dbhost, $dbuser, $dbpw, $dbname = ”, $pconnect = 0){    if($this->link_rw == null)      $this->link_rw = $this->link;    $this->link = null;    //不产生halt错误    $this->connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect, false);    if($this->link){      //连接成功      //echo “link ro sussess!<br>”;      $this->ro_exist = true;      $this->link_ro = $this->link;      if($this->cur_db){        //如果已经选择过数据库则需要操作一次        @mysql_select_db($this->cur_db, $this->link_ro);      }    }else{      //连接失败      //echo “link ro failed!<br>”;      $this->link = &$this->link_rw;    }  }  //设置一系列只读数据库并且连接其中一个  function set_ro_list($ro_list){    if(is_array($ro_list)){      //随机选择其中一个      $link_ro = $ro_list[array_rand($ro_list)];      $this->connect_ro($link_ro['dbhost'], $link_ro['dbuser'], $link_ro['dbpw']);    }  }  function select_db($dbname) {    //同时操作两个数据库连接    $this->cur_db = $dbname;    if($this->ro_exist){      @mysql_select_db($dbname, $this->link_ro);    }    return @mysql_select_db($dbname, $this->link_rw);  }  function fetch_array($query, $result_type = MYSQL_ASSOC) {    return mysql_fetch_array($query, $result_type);  }  function fetch_one_array($sql, $type = ”) {    $qr = $this->query($sql, $type);    return $this->fetch_array($qr);  }  function query($sql, $type = ”) {    $this->link = &$this->link_rw;    //判断是否select语句    if($this->ro_exist && PReg_match (”/^(/s*)select/i”, $sql)){      $this->link = &$this->link_ro;    }    $func = $type == ‘UNBUFFERED’ && @function_exists(’mysql_unbuffered_query’) ?      ‘mysql_unbuffered_query’ : ‘mysql_query’;    if(!($query = $func($sql, $this->link)) && $type != ‘SILENT’) {      $this->halt(’MySQL Query Error’, $sql);    }    $this->querynum++;    return $query;  }  function affected_rows() {    return mysql_affected_rows($this->link);  }  function error() {    return (($this->link) ? mysql_error($this->link) : mysql_error());  }  function errno() {    return intval(($this->link) ? mysql_errno($this->link) : mysql_errno());  }  function result($query, $row) {    $query = @mysql_result($query, $row);    return $query;  }  function num_rows($query) {    $query = mysql_num_rows($query);    return $query;  }  function num_fields($query) {    return mysql_num_fields($query);  }  function free_result($query) {    return mysql_free_result($query);  }  function insert_id() {    return ($id = mysql_insert_id($this->link)) >= 0 ? $id : $this->result($this->query(”SELECT last_insert_id()”), 0);  }  function fetch_row($query) {    $query = mysql_fetch_row($query);    return $query;  }  function fetch_fields($query) {    return mysql_fetch_field($query);  }  function version() {    return mysql_get_server_info($this->link);  }  function close() {    return mysql_close($this->link);  }  function halt($message = ”, $sql = ”) {    $dberror = $this->error();    $dberrno = $this->errno();    echo “<div style=/”position:absolute;font-size:11px;font-family:verdana,arial;background:#EBEBEB;padding:0.5em;/”>        <b>MySQL Error</b><br>        <b>Message</b>: $message<br>        <b>SQL</b>: $sql<br>        <b>Error</b>: $dberror<br>        <b>Errno.</b>: $dberrno<br>        </div>”;    exit();  }}?>