下面的代碼是用此前一個(gè)名為MyPDO的類改寫的,引入了單例模式來保證在全局調(diào)用中不會(huì)重復(fù)實(shí)例化這個(gè)類,降低系統(tǒng)資源的浪費(fèi),用php大部分操作都是和各種數(shù)據(jù)庫打交道,包括mysql,redis,memcache等各種關(guān)系型和非關(guān)系型數(shù)據(jù)庫,所以一個(gè)應(yīng)用中會(huì)存在大量連接數(shù)據(jù)庫的操作,如果不用單例模式,那每次都要new操作,但是每次new都會(huì)消耗大量的內(nèi)存資源和系統(tǒng)資源,而且每次打開和關(guān)閉數(shù)據(jù)庫連接都是對(duì)數(shù)據(jù)庫的一種極大考驗(yàn)和浪費(fèi),代碼如下:

<?php
class MyPDO {
    protected static $_instance = null;
    protected $dbName = &#39;&#39;;
    protected $dsn;
    protected $dbh;
    /** 
     * 構(gòu)造
     *
     * @return MyPDO
     */
    private function __construct($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset) {
        try {
            $this->dsn = &#39;mysql:host=&#39; . $dbHost . &#39;;dbname=&#39; . $dbName;
            $this->dbh = new PDO($this->dsn, $dbUser, $dbPasswd);
            $this->dbh->exec(&#39;SET character_set_connection=&#39; . $dbCharset . &#39;, character_set_results=&#39; . $dbCharset . &#39;, character_set_client=binary&#39;);
        }
        catch(PDOException $e) {
            $this->outputError($e->getMessage());
        }
    }
    /** 
     * 防止克隆
     *
     */
    private function __clone() {
    }
    /** 
     * Singleton instance
     *
     * @return Object
     */
    public static function getInstance($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset) {
        if (self::$_instance === null) {
            self::$_instance = new self($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset);
        }
        return self::$_instance;
    }
    /** 
     * Query 查詢
     *
     * @param String $strSql SQL語句
     * @param String $queryMode 查詢方式(All or Row)
     * @param Boolean $debug
     * @return Array
     */
    public function query($strSql, $queryMode = &#39;All&#39;, $debug = false) {
        if ($debug === true) $this->debug($strSql);
        $recordset = $this->dbh->query($strSql);
        $this->getPDOError();
        if ($recordset) {
            $recordset->setFetchMode(PDO::FETCH_ASSOC);
            if ($queryMode == &#39;All&#39;) {
                $result = $recordset->fetchAll();
            } elseif ($queryMode == &#39;Row&#39;) {
                $result = $recordset->fetch();
            }
        } else {
            $result = null;
        }
        return $result;
    }
    /** 
     * Update 更新
     *
     * @param String $table 表名
     * @param Array $arrayDataValue 字段與值
     * @param String $where 條件
     * @param Boolean $debug
     * @return Int
     */
    public function update($table, $arrayDataValue, $where = &#39;&#39;, $debug = false) {
        $this->checkFields($table, $arrayDataValue);
        if ($where) {
            $strSql = &#39;&#39;;
            foreach ($arrayDataValue as $key => $value) {
                $strSql.= ", `$key`=&#39;$value&#39;";
            }
            $strSql = substr($strSql, 1);
            $strSql = "UPDATE `$table` SET $strSql WHERE $where";
        } else {
            $strSql = "REPLACE INTO `$table` (`" . implode(&#39;`,`&#39;, array_keys($arrayDataValue)) . "`) VALUES (&#39;" . implode("&#39;,&#39;", $arrayDataValue) . "&#39;)";
        }
        if ($debug === true) $this->debug($strSql);
        $result = $this->dbh->exec($strSql);
        $this->getPDOError();
        return $result;
    }
    /** 
     * Insert 插入
     *
     * @param String $table 表名
     * @param Array $arrayDataValue 字段與值
     * @param Boolean $debug
     * @return Int
     */
    public function insert($table, $arrayDataValue, $debug = false) {
        $this->checkFields($table, $arrayDataValue);
        $strSql = "INSERT INTO `$table` (`" . implode(&#39;`,`&#39;, array_keys($arrayDataValue)) . "`) VALUES (&#39;" . implode("&#39;,&#39;", $arrayDataValue) . "&#39;)";
        if ($debug === true) $this->debug($strSql);
        $result = $this->dbh->exec($strSql);
        $this->getPDOError();
        return $result;
    }
    /** 
     * Replace 覆蓋方式插入
     *
     * @param String $table 表名
     * @param Array $arrayDataValue 字段與值
     * @param Boolean $debug
     * @return Int
     */
    public function replace($table, $arrayDataValue, $debug = false) {
        $this->checkFields($table, $arrayDataValue);
        $strSql = "REPLACE INTO `$table`(`" . implode(&#39;`,`&#39;, array_keys($arrayDataValue)) . "`) VALUES (&#39;" . implode("&#39;,&#39;", $arrayDataValue) . "&#39;)";
        if ($debug === true) $this->debug($strSql);
        $result = $this->dbh->exec($strSql);
        $this->getPDOError();
        return $result;
    }
    /** 
     * Delete 刪除
     *
     * @param String $table 表名
     * @param String $where 條件
     * @param Boolean $debug
     * @return Int
     */
    public function delete($table, $where = &#39;&#39;, $debug = false) {
        if ($where == &#39;&#39;) {
            $this->outputError("&#39;WHERE&#39; is Null");
        } else {
            $strSql = "DELETE FROM `$table` WHERE $where";
            if ($debug === true) $this->debug($strSql);
            $result = $this->dbh->exec($strSql);
            $this->getPDOError();
            return $result;
        }
    }
    /** 
     * execSql 執(zhí)行SQL語句
     *
     * @param String $strSql
     * @param Boolean $debug
     * @return Int
     */
    public function execSql($strSql, $debug = false) {
        if ($debug === true) $this->debug($strSql);
        $result = $this->dbh->exec($strSql);
        $this->getPDOError();
        return $result;
    }
    /** 
     * 獲取字段最大值
     *
     * @param string $table 表名
     * @param string $field_name 字段名
     * @param string $where 條件
     */
    public function getMaxValue($table, $field_name, $where = &#39;&#39;, $debug = false) {
        $strSql = "SELECT MAX(" . $field_name . ") AS MAX_VALUE FROM $table";
        if ($where != &#39;&#39;) $strSql.= " WHERE $where";
        if ($debug === true) $this->debug($strSql);
        $arrTemp = $this->query($strSql, &#39;Row&#39;);
        $maxValue = $arrTemp["MAX_VALUE"];
        if ($maxValue == "" || $maxValue == null) {
            $maxValue = 0;
        }
        return $maxValue;
    }
    /** 
     * 獲取指定列的數(shù)量
     *
     * @param string $table
     * @param string $field_name
     * @param string $where
     * @param bool $debug
     * @return int
     */
    public function getCount($table, $field_name, $where = &#39;&#39;, $debug = false) {
        $strSql = "SELECT COUNT($field_name) AS NUM FROM $table";
        if ($where != &#39;&#39;) $strSql.= " WHERE $where";
        if ($debug === true) $this->debug($strSql);
        $arrTemp = $this->query($strSql, &#39;Row&#39;);
        return $arrTemp[&#39;NUM&#39;];
    }
    /** 
     * 獲取表引擎
     *
     * @param String $dbName 庫名
     * @param String $tableName 表名
     * @param Boolean $debug
     * @return String
     */
    public function getTableEngine($dbName, $tableName) {
        $strSql = "SHOW TABLE STATUS FROM $dbName WHERE Name=&#39;" . $tableName . "&#39;";
        $arrayTableInfo = $this->query($strSql);
        $this->getPDOError();
        return $arrayTableInfo[0][&#39;Engine&#39;];
    }
    /** 
     * beginTransaction 事務(wù)開始
     */
    private function beginTransaction() {
        $this->dbh->beginTransaction();
    }
    /** 
     * commit 事務(wù)提交
     */
    private function commit() {
        $this->dbh->commit();
    }
    /** 
     * rollback 事務(wù)回滾
     */
    private function rollback() {
        $this->dbh->rollback();
    }
    /** 
     * transaction 通過事務(wù)處理多條SQL語句
     * 調(diào)用前需通過getTableEngine判斷表引擎是否支持事務(wù)
     *
     * @param array $arraySql
     * @return Boolean
     */
    public function execTransaction($arraySql) {
        $retval = 1;
        $this->beginTransaction();
        foreach ($arraySql as $strSql) {
            if ($this->execSql($strSql) == 0) $retval = 0;
        }
        if ($retval == 0) {
            $this->rollback();
            return false;
        } else {
            $this->commit();
            return true;
        }
    }
    /** 
     * checkFields 檢查指定字段是否在指定數(shù)據(jù)表中存在
     *
     * @param String $table
     * @param array $arrayField
     */
    private function checkFields($table, $arrayFields) {
        $fields = $this->getFields($table);
        foreach ($arrayFields as $key => $value) {
            if (!in_array($key, $fields)) {
                $this->outputError("Unknown column `$key` in field list.");
            }
        }
    }
    /** 
     * getFields 獲取指定數(shù)據(jù)表中的全部字段名
     *
     * @param String $table 表名
     * @return array
     */
    private function getFields($table) {
        $fields = array();
        $recordset = $this->dbh->query("SHOW COLUMNS FROM $table");
        $this->getPDOError();
        $recordset->setFetchMode(PDO::FETCH_ASSOC);
        $result = $recordset->fetchAll();
        foreach ($result as $rows) {
            $fields[] = $rows[&#39;Field&#39;];
        }
        return $fields;
    }
    /** 
     * getPDOError 捕獲PDO錯(cuò)誤信息
     */
    private function getPDOError() {
        if ($this->dbh->errorCode() != &#39;00000&#39;) {
            $arrayError = $this->dbh->errorInfo();
            $this->outputError($arrayError[2]);
        }
    }
    /** 
     * debug
     *
     * @param mixed $debuginfo
     */
    private function debug($debuginfo) {
        var_dump($debuginfo);
        exit();
    }
    /** 
     * 輸出錯(cuò)誤信息
     *
     * @param String $strErrMsg
     */
    private function outputError($strErrMsg) {
        throw new Exception(&#39;MySQL Error: &#39; . $strErrMsg);
    }
    /** 
     * destruct 關(guān)閉數(shù)據(jù)庫連接
     */
    public function destruct() {
        $this->dbh = null;
    }
}

調(diào)用方法:

<?php
require &#39;MyPDO.class.php&#39;;
$db = MyPDO::getInstance(&#39;localhost&#39;, &#39;root&#39;, &#39;123456&#39;, &#39;test&#39;, &#39;utf8&#39;);
//do something...
$db->destruct();

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隨意轉(zhuǎn)載^^但請(qǐng)附上教程地址。