本代碼是從uchome的代碼修改的，是因為要解決uchome的效率而處理的。封裝的方式比較簡單，增加了只讀數據庫連接的接口擴展，不使用只讀數據庫也不影響原代碼使用。有待以后不斷完善。。

為了方便，試試建立了google的一個項目：http://code.google.com/p/mysql-rw-php/

希望給有需要的朋友帶來幫助。

PHP實現的Mysql讀寫分離

主要特性：

簡單的讀寫分離一個主數據庫，可以添加更多的只讀數據庫讀寫分離但不用擔心某些特性不支持缺點：同時連接兩個數據庫英文比較爛，也寫幾個字吧

php code for mysql read/write splitfeature:simply rw splitone master,can add more slavessupport all mysql featurelink to the master and slave at the same time

PHP代碼：

mysql_rw_php.class.php

<?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 { //查詢個數 var $querynum = 0; //當前操作的數據庫連接 var $link = null; //字符集 var $charset; //當前數據庫 var $cur_db = ”; //是否存在有效的只讀數據庫連接 var $ro_exist = false; //只讀數據庫連接 var $link_ro = null; //讀寫數據庫連接 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 && $this->halt(’Can not connect to MySQL server’); } } //只讀連接失敗 if(!$this->link && !$halt) return false; //未初始化rw時，第一個連接作為rw if($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.mypchelp.cn/php.asp 連接一個只讀的mysql數據庫 function connect_ro($dbhost, $dbuser, $dbpw, $dbname = ”, $pconnect = 0){ if($this->link_rw == null) $this->link_rw = $this->link; $this->link = null; //不產生halt錯誤 $this->connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect, false); if($this->link){ //連接成功 //echo “link ro sussess!<br>”; $this->ro_exist = true; $this->link_ro = $this->link; if($this->cur_db){ //如果已經選擇過數據庫則需要操作一次 @mysql_select_db($this->cur_db, $this->link_ro); } }else{ //連接失敗 //echo “link ro failed!<br>”; $this->link = &$this->link_rw; } } //設置一系列只讀數據庫并且連接其中一個 function set_ro_list($ro_list){ if(is_array($ro_list)){ //隨機選擇其中一個 $link_ro = $ro_list[array_rand($ro_list)]; $this->connect_ro($link_ro['dbhost'], $link_ro['dbuser'], $link_ro['dbpw']); } } function select_db($dbname) { //同時操作兩個數據庫連接 $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; //判斷是否select語句 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(); }}?>example.php

<?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)****************************************/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];}?>