php pdo公共类

db.class.php ：

<?php

class db extends \PDO {

    private static $_instance = null;
    protected $dbName = '';
    protected $dsn;
    protected $dbh;

    public function __construct($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset='utf8') {
        try {
            $this->dsn = 'mysql:host=' . $dbHost . ';dbname=' . $dbName;
            $this->dbh = new \PDO($this->dsn, $dbUser, $dbPasswd);
            $this->dbh->setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);
            $this->dbh->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
            $this->dbh->exec('SET character_set_connection='.$dbCharset.';SET character_set_client='.$dbCharset.';SET character_set_results='.$dbCharset);
        } catch (Exception $e) {
            $this->outputError($e->getMessage());  
        }
    }

    public static function getInstance($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset='utf8') {
        if (self::$_instance === null) {
            self::$_instance = new self($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset);
        }
        return self::$_instance;
    }

    public function fetchAll($sql, $params = array()) {
        try {
            $stm = $this->dbh->prepare($sql);
            if ($stm && $stm->execute($params)) {
                return $stm->fetchAll(\PDO::FETCH_ASSOC);
            }
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }
    }

    public function fetchOne($sql, $params = array()) {
        try {
            $result = false;
            $stm = $this->dbh->prepare($sql);
            if ($stm && $stm->execute($params)) {
                $result = $stm->fetch(\PDO::FETCH_ASSOC);
            }
            return $result;
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }
    }

    public function fetchColumn($sql, $params = array()) {
        $result = '';
        try {
            $stm = $this->dbh->prepare($sql);
            if ($stm && $stm->execute($params)) {
                $result = $stm->fetchColumn();
            }
            return $result;
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }
    }

    public function insert($table, $params = array(), $returnLastId = true) {
        $_implode_field = '';
        $fields = array_keys($params);
        $_implode_field = implode(',', $fields);

        $_implode_value = '';
        foreach ($fields as $value) {
            $_implode_value .= ':'. $value.',';
        }
        $_implode_value = trim($_implode_value, ',');

        $sql = 'INSERT INTO ' . $table . '(' . $_implode_field . ') VALUES ('.$_implode_value.')';

        try {
            $stm = $this->dbh->prepare($sql);
            $result = $stm->execute($params);
            if ( $returnLastId ) {
                $result = $this->dbh->lastInsertId();
            }
            return $result;
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }

    }

    public function update($table, $params = array(), $where = null) {
        $_implode_field = '';
        $_implode_field_arr = array();

        if ( empty($where) ) {
            return false;
        }

        $fields = array_keys($params);

        foreach ($fields as $key) {
            $_implode_field_arr[] = $key . '=' . ':'.$key;
        }

        $_implode_field = implode(',', $_implode_field_arr);
        $sql = 'UPDATE ' . $table . ' SET ' . $_implode_field . ' WHERE ' . $where;
        try {
            $stm = $this->dbh->prepare($sql);
            $result = $stm->execute($params);
            return $result;
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }

    }

    public function delete($sql, $params = array()) {
        try {
            $stm = $this->dbh->prepare($sql);
            $result = $stm->execute($params);
            return $result;
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }
    }


    public function exec($sql, $params = array()) {
        try {
            $stm = $this->dbh->prepare($sql);
            $result = $stm->execute($params);
            return $result;
        } catch (Exception $e) {
            $this->outputError($e->getMessage());
        }
    }

    private function outputError($strErrMsg) {
        throw new Exception("MySQL Error: " . $strErrMsg);
    }

    public function __destruct() {
        $this->dbh = null;
        self::$_instance = null;
    }
}

实例：

<?php
require_once './db.class.php';

$pdo = db::getInstance('127.0.0.1', 'root', '111111', 'php_cms');

$sql = "select id, title1 from cms_wz where id = :id limit 1";
$parame = array('id' => 12,);

$res = $pdo->fetchOne($sql, $parame);
var_dump($res);


$sql = 'SELECT * FROM cms_link';
$result = $db->fetchAll($sql);
print_r($result);

//查询记录数量
$sql = 'SELECT COUNT(*) FROM cms_link';
$count = $db->fetchColumn($sql);
echo $count;


$data = array(
    'siteid' => 1,
    'linktype' => 1,
    'name' => 'google',
    'url' => 'http://www.google.com',
    'listorder' => 0,
    'elite' => 0,
    'passed' => 1,
    'addtime' => time()
    );
$lastInsertId = $db->insert('cms_link', $data);
echo $lastInsertId;
//用 try
 try {
         $result = $pdo->insert('news', $essay);
     } catch (Exception $e) {
         error_log($e->getMessage());
         error_log($e->getMessage() . ' in ' . __FILE__ . ' on line ' . __LINE__);
         saveLog('url文章 :  ' . $essay['link'] . '   数据插入失败<br>');
         continue;
     }

$data = array(
    'siteid' => 1,
    'linktype' => 1,
    'name' => 'google',
    'url' => 'http://www.google.com',
    'listorder' => 0,
    'elite' => 0,
    'passed' => 1,
    'addtime' => time()
    );
$db->insert('cms_link', $data);



$sql = 'DELETE FROM cms_link WHERE linkid=4';

$result = $db->delete($sql);
var_dump($result);