创建数据库连接类(PDO)并获取数据

问题描述

我是OOP的新手，所以我试图学习如何创建类并使用它们.目前，我正在尝试从MySQL表中获取数据.

I am new to OOP, so I am trying to learn how to create classes and use them. Currently I am trying to fetch data from my MySQL table.

要创建与MySQL的连接，我正在使用PDO.我为数据库连接创建了一个单独的类.我已经在show.php文件中包含了该类.现在，我想从MySQL数据库中获取数据.问题是当我运行show.php文件时，它显示此错误消息

To create the connection with MySQL I am using PDO. I have created a separate class for database connection. I have included the class in my show.php file. Now I want to fetch data from MySQL database. The problem is when I run my show.php file it shows this error message

但是应该只显示array.

该问题的解决方案是什么?

What is the solution to this problem?

<?php
    class DBConnection {

        function DBConnection(){

            $host = 'localhost';
            $dbname = 'srijon';
            $user = 'root';
            $pass = '';

            try {
                $DBH = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
                $DBH->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

                return $DBH;
            }
            catch(PDOException $e) {

                echo 'ERROR: ' . $e->getMessage();
            }

        } // function ends

    } // class ends
?>

文件 show.php

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

    function get_all(){

        $db = new DBConnection();

        $sql = "SELECT * FROM information";
        $STH = $db->prepare($sql);
        $STH->execute();
        $STH->setFetchMode(PDO::FETCH_ASSOC);

        return $STH;
    }

    echo get_all();
?>

推荐答案

恕我直言，您可以将PDO连接注入到需要它的函数中:

IMHO you can just inject the PDO connection into the functions that need it:

<?php

$dbHandle = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
$dbHandle->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// always disable emulated prepared statement when using the MySQL driver
$dbHandle->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

function get_all($dbHandle) {
    $sql = "SELECT * FROM information";
    $stmt = $dbHandle->prepare($sql);
    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);

    return $stmt;
}

get_all($dbHandle);

如果您确实认为需要某种类来访问数据库(PDO除外)(不需要)，则必须扩展PDO:

If you really think you need some class to access to database (other than PDO) (which you don't need) you would have to extend PDO:

<?php

class DBConnection extends PDO
{
    public function __construct()
    {
        parent::__construct("mysql:host=$host;dbname=$dbname", $user, $pass);
        $this->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        // always disable emulated prepared statement when using the MySQL driver
        $this->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
    }
}

$dbHandle = new DBConnection();

function get_all($dbHandle) {
    $sql  = "SELECT * FROM information";
    $stmt = $dbHandle->prepare($sql);
    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);

    return $stmt;
}

get_all($dbHandle);

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