本代码是从uchome的代码修改的，是因为要解决uchome的效率而处理的。 PHP实现的Mysql读写分离

        主要特性:

        简单的读写分离

        一个主数据库，可以添加更多的只读数据库

        读写分离但不用担心某些特性不支持

        缺点:同时连接两个数据库

        英文比较烂，也写几个字吧

        php code for mysql read/write split feature:

        simply rw split

        one master,can add more slaves support all mysql feature

        link to the master and slave at the same time

        PHP代码:

        mysql_rw_php.class.php

        <?php

        /**************************************** *** mysql-rw-php version 0.1 @ 2009-4-16 *** code by hqlulu#gmail.com

        ***

        *** *** 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);

        }

        }

        //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_quewww.shanxiwang.netry' : '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();

        }

        }

        ?>

        example.php

        <?php

        /**************************************** *** mysql-rw-php version 0.1 @ 2009-4-16 *** code by hqlulu#gmail.com

        ***

        *** *** code modify from class_mysql.php (uchome) ****************************************/ require_once('mysql_rw_php.class.php'); //rw info

        $db_rw = array(

        'dbhost'=>'www.aslibra.com',

        'dbuser'=>'aslibra',

        'dbpw'=>'www.aslibra.com',

        'dbname'=>'test'

        );

        $db_ro = array(

        array(

        'dbhost'=>'www.aslibra.com:4306',

        'dbuser'=>'aslibra',

        'dbpw'=>'www.aslibra.com'

        )

        );

        $DB = new mysql_rw_php;

        //connect Master

        $DB->connect($db_rw[dbhost], $db_rw[dbuser], $db_rw[dbpw], $db_rw[dbname]);

        //Method 1: connect one server

        $DB->connect_ro($db_ro[0][dbhost], $db_ro[0][dbuser], $db_ro[0][dbpw]);

        //Method 2: connect one server from a list by rand

        $DB->set_ro_list($db_ro); //send to rw

        $sql = "insert into a set a='test'"; $DB->query($sql);

        //send to ro

        $sql = "select * from a"; $qr = $DB->query($sql);

        while($row = $DB->fetch_array($qr)){

        echo $row[a];

        }

        ?>