所以我有一个用于连接到数据库的辅助类，但现在我希望能够使用相同的类连接到同一代码块中的不同数据库。
帮助程序类：
<?php
require_once 'config.php'; // Database setting constants [DB_HOST, DB_NAME, DB_USERNAME, DB_PASSWORD]
class dbHelper {
private $db;
private $err;
function __construct() {
$dsn = 'mysql:host='.DB_HOST.';dbname='.DB_NAME.';charset=utf8';
try {
$this->db = new PDO($dsn, DB_USERNAME, DB_PASSWORD, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
} catch (PDOException $e) {
$response["status"] = "error";
$response["message"] = 'Connection failed: ' . $e->getMessage();
$response["data"] = null;
exit;
}
}
function select($table, $where){
try{
$a = array();
$w = "";
foreach ($where as $key => $value) {
$w .= " and " .$key. " like :".$key;
$a[":".$key] = $value;
}
$stmt = $this->db->prepare("select * from ".$table." where 1=1 ". $w);
$stmt->execute($a);
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
if(count($rows)<=0){
$response["status"] = "warning";
$response["message"] = "No data found.";
}else{
$response["status"] = "success";
$response["message"] = "Data selected from database";
}
$response["data"] = $rows;
}catch(PDOException $e){
$response["status"] = "error";
$response["message"] = 'Select Failed: ' .$e->getMessage();
$response["data"] = null;
}
return $response;
}
}
因此，您可以通过设置常量然后调用函数来调用上述内容：
数据库配置.php
<?php
/**
* Database configuration
*/
define('DB_USERNAME', 'root');
define('DB_PASSWORD', '');
define('DB_HOST', 'localhost');
define('DB_NAME', 'database1');
?>
页.php
<?php
require_once 'dbHelper.php';
$db = new dbHelper();
$rows = $db->select("customers_php",array());
print_r(json_encode($rows,JSON_NUMERIC_CHECK));
?>
我想放弃对 config.php 文件的需求，并将DB_HOST、DB_NAME等移动到类内部的函数中，并将数据库名称以及$table和$where信息一起传递。
if($db_name == 'database1')
{
//#----------open database connection --------------------> TESTING
$db_host = "localhost";
$db_user = "root";
$db_password = "";
$db_name = "database1";
}
if($db_name == 'database2')
{
//#----------open database connection --------------------> TESTING
$db_host = "localhost";
$db_user = "root";
$db_password = "";
$db_name = "database2";
}
新页.php
<?php
require_once 'dbHelper.php';
$db = new dbHelper();
//function select($dbname, $table, $where)......................
$rows = $db->select("database1","customers_php",array());
print_r(json_encode($rows,JSON_NUMERIC_CHECK));
?>
那么，我可以/可以在哪里放置"if（$dbname）"部分？
您可以将if($dbname)部分放入config.php，然后按以下方式修改dbHelper类：
class dbHelper
{
public function __construct( $db_host, $db_user, $db_password, $db_name )
{
(...)
}
(...)
}
并以此方式调用它：
$db = new dbHelper( $db_host, $db_user, $db_password, $db_name );
编辑：
我认为为每个连接维护一个实例可能更好，但是 - 如果您想即时更改它 - 您可以将您的类修改为：
class dbHelper
{
function __construct( $db_host, $db_user, $db_password, $db_name )
{
$this->connect( $db_host, $db_user, $db_password, $db_name );
}
function dbSelect( $db_host, $db_user, $db_password, $db_name )
{
if( $this->db ) $this->db = Null;
$dsn = 'mysql:host='.$db_host.';dbname='.$db_name.';charset=utf8';
try {
$this->db = new PDO($dsn, $db_user, $db_password, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
} catch (PDOException $e) {
$response["status"] = "error";
$response["message"] = 'Connection failed: ' . $e->getMessage();
$response["data"] = null;
exit;
}
}
(...)
}
然后通过dbHelper->dbSelect()更改数据库连接。