mysqli::query(): 无法获取 mysqli

Question

警告：mysqli::query(): Couldn't fetch mysqli in C:\Program Files (x86)\EasyPHP-DevServer-13.1VC9\data\localweb\my便携式文件\class_EventCalendar.php on line 43

以下是我的连接文件：

<?php
if(!isset($_SESSION)) 
{ 
    session_start(); 
}  

// Create array to hold error messages (if any)
$ErrorMsgs = array();

// Create new mysql connection object
$DBConnect = @new mysqli("localhost","root@localhost", 
            NULL,"Ladle");

// Check to see if connection errno data member is not 0 (indicating an error)
if ($DBConnect->connect_errno) {

    // Add error to errors array
    $ErrorMsgs[]="The database server is not available.".
               " Connect Error is ".$DBConnect->connect_errno." ".
               $DBConnect->connect_error.".";
}
?>

这是我的课：

 <?php 
    class EventCalendar {
        private $DBConnect = NULL;

        function __construct() {
            // Include the database connection data
            include("inc_LadleDB.php");
            $this->DBConnect = $DBConnect;  
        }

        function __destruct() {
            if (!$this->DBConnect->connect_error) {
                $this->DBConnect->close();
            }
        }

        function __wakeup() {
            // Include the database connection data
            include("inc_LadleDB.php");     
            $this->DBConnect = $DBConnect;
        }


        // Function to add events to Zodiac calendar
        public function addEvent($Date, $Title, $Description) {
            // Check to see if the required fields of Date and Title have been entered
            if ((!empty($Date)) && (!empty($Title))) {
                /* if all fields are complete then they are 
                   inserted into the Zodiac event_calendar table */
                $SQLString = "INSERT INTO tblSignUps".
                           " (EventDate, Title, Description) ".
                           " VALUES('$Date', '$Title', '".
                            $Description."')";

                // Store query results in a variable
                $QueryResult = $this->DBConnect->query($SQLString);

我对 OOP PHP 不是很好，我不确定为什么会出现这个错误。我从其他地方提取了这段代码，唯一改变的是@new mysqli 参数。谁能帮我理解出了什么问题？

Answer 1

我遇到了同样的问题。我将 mysqli 对象中的 localhost 参数更改为“127.0.0.1”，而不是写“localhost”。有效;我不确定如何或为什么。

$db_connection = new mysqli("127.0.0.1","root","","db_name");

Answer 2

可能在您有 DBconnection->close(); 的某个地方，然后尝试执行一些查询。

---

提示：在__destruct()中插入...->close();有时是错误的（因为__destruct是事件，之后会有需要执行查询）

Answer 3

检查数据库名称是否没有“_”或“-” 这对我有帮助

Answer 4

错误原因是mysqli对象初始化错误。真正的构造应该是这样的：

$DBConnect = new mysqli("localhost","root","","Ladle");