php实现的pdo公共类定义与用法示例

本文实例讲述了php实现的pdo公共类定义与用法。分享给大家供大家参考，具体如下：

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;
  }
}

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);

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希望本文所述对大家PHP程序设计有所帮助。