在同一数据库对象上使用pdo query()和自定义getValue()?

问题描述

class connector {
  private static $db;
  function __construct() {
    $this->db = null;
    $this->connect();
  }
  private function connect() {
    $this->db = new PDO('mysql:host=localhost;dbname=database;charset=utf8','user','pass');
  }
  public static function getDB() {
    if (!isset(self::$db)) {
      self::$db = new connector();
    }
    return self::$db;
  }

已编辑

  // this was my original function, I had reduced it for less space. my deepest regrets, I won't do it again.
  public function getValue($sql,$val='') {
    if ($val != '') {
      $data = $this->db->prepare($sql);
      $data->execute($val);
      return $data->fetch(PDO::FETCH_COLUMN);
    }
    else {
      return $this->db->query($sql)->fetch(PDO::FETCH_COLUMN);
    }

使用此类，我可以通过自定义函数轻松地在任何地方使用pdo数据库对象.

using this class I can easily use the pdo database object from anywhere, with custom functions.

$db = connector::getDB();

// var_dump()
db:object(connector)#1 (1) {
  ["db":"connector":private]=>
  object(PDO)#2 (0) {
  }
}

$db->getValue('SELECT foo FROM bar'); //succeeds

$db->query('SELECT foo FROM bar'));
// throws
// Fatal error:  Call to undefined method connector::query()

如果我返回实际的对象参数而不是整个对象:

if I return the actual object param instead of the whole object:

return self::$db->db;
db:object(PDO)#2 (0) {
}

查询交换角色

$db->getValue('SELECT foo FROM bar');
// throws
// Fatal error:  Call to undefined method connector::getValue()

$db->query('SELECT foo FROM bar')); //succeeds

如何在同一个脚本中有效地使用$db->query()和$db->getValue()来使两个对象同一个对象.

How can I have both with the same object, effectively using $db->query() and $db->getValue() in the same script.

推荐答案

首先，您的getValue()方法缺乏一项基本功能-对准备好的语句的支持.没有运行动态查询的能力，它的价值几乎为零.

First of all, your getValue() method lacks one essential feature - support for prepared statements. Without ability to run dynamical queries it's value is close to nothing.

第二，无论如何，如果您正在使用单例-则不需要额外的方法来获取实例-如今，单例可以自己完成.

Second, if you are using a singleton anyway - then there is no need for the extra method to get an instance - nowadays singleton can do it just by itself.

那是什么呢?我编写它的目的是利用整洁的方法链来减少PDO的使用难度. DB静态类已经是 一个PDO实例，无需通过额外的调用实例化它.因此，您可以在任何地方运行任何PDO命令:

What about this one? I wrote it to make PDO usage less wordy, utilizing neat method chaining. DB static class is already a PDO instance, without the need to instantiate it with extra call. As a result, you can run any PDO command just anywhere:

DB::query('SELECT foo FROM bar LIMIT 1')->fetchColumn();

占用的空间比您少，但至少可以让您访问完整的PDO语法，包括对准备好的语句的支持

It takes little more space than yours but at least it is giving you access to full PDO syntax, including support for prepared statements

DB::prepare('SELECT foo FROM bar WHERE id=?')->execite([$id])->fetchColumn();

以及所有其他提取方法

DB::query('SELECT foo FROM bar')->fetchAll(PDO::FETCH_COLUMN);

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