當我通過 xampp 運行我的代碼時，我一直遇到這個錯誤。即使在啟動 MySQL 和 Apache 之后警告: mysqli_connect(): (HY000/1049): Unknown database 'loginsystem' in C:\xampp\htdocs\dbconnection.php on line 6 Failed to connect to MySQL: Unknown database 'loginsystem'這是我的 db.connection 代碼<?phpdefine('DB_SERVER','localhost');define('DB_USER','root');define('DB_PASS' ,'');define('DB_NAME', 'loginsystem');$con = mysqli_connect(DB_SERVER,DB_USER,DB_PASS,DB_NAME);// Check connectionif (mysqli_connect_errno())  {   echo "Failed to connect to MySQL: " . mysqli_connect_error();  } ?>loginsystem.sql-- phpMyAdmin SQL Dump-- version 4.8.4-- https://www.phpmyadmin.net/---- Host: 127.0.0.1-- Generation Time: Mar 24, 2019 at 05:58 PM-- Server version: 10.1.37-MariaDB-- PHP Version: 7.3.0SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";SET AUTOCOMMIT = 0;START TRANSACTION;SET time_zone = "+00:00";/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;/*!40101 SET NAMES utf8mb4 */;---- Database: `loginsystem`---- ------------------------------------------------------------ Table structure for table `admin`--CREATE TABLE `admin` (`id` int(11) NOT NULL, `username` varchar(255) NOT NULL,`password` varchar(255) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1;  ---- Dumping data for table `admin`--INSERT INTO `admin` (`id`, `username`, `password`) VALUES(1, 'admin', 'dd077f889d7e3641bf9cc0e64b157918'); -- ------------------------------------------------------------ Table structure for table `off`--CREATE TABLE `off` (`id` int(11) NOT NULL,`dateoff` date NOT NULL,`timeoff` text NOT NULL,`dateback` date NOT NULL,`timeback` text NOT NULL,`reason` text NOT NULL,`status` text NOT NULL) ENGINE=InnoDB DEFAULT CHARSET=latin1;我不斷收到此錯誤。它不允許我登錄警告: mysqli_connect(): (HY000/1049): Unknown database 'loginsystem' in C:\xampp\htdocs\dbconnection.php on line 6 Failed to connect to MySQL: Unknown database 'loginsystem'