php pdo公共类

db.class.php ：

<?phpclass 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;    }}

实例：

<?phprequire_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);