在php中出現致命錯誤

Question

我正在嘗試解決此問題。但無法做到這一點。請幫助

我想在我的數據庫，查看所有的記錄，但獲得「致命錯誤：調用一個成員函數查詢（）非對象....上」，其指向

if ($result = $mysqli->query("SELECT ProductName, Description, Price, Size FROM Products ORDER BY ProductID")) 

這裏是我的完整代碼

<?php 

         include('db_connect.php'); 

**$mysqli = new mysqli("localhost", "netelmbn", "password", "netelmbn"); 
         if ($mysqli->connect_errno) { 
    printf("Connect failed: %s\n", $mysqli->connect_error); 
    exit(); 
}** 


         if ($result = $mysqli->query("SELECT ProductName, Description, Price, Size FROM Products ORDER BY ProductID")) 
         { 

           if ($result->num_rows > 0) 
           { 

             echo "<table border='1' cellpadding='10'>"; 


             echo "<tr><th>ProductID</th><th>ProductName</th><th>Description</th><th>Price</th><th>Size</th></tr>"; 

             while ($row = $result_fetch_object()) 
             { 

               echo "<tr>"; 
               echo "<td>" . $row->ProductID . "</td>"; 
               echo "<td>" . $row->ProductName . "</td>"; 
               echo "<td>" . $row->Description . "</td>"; 
               echo "<td>" . $row->Price . "</td>"; 
               echo "<td>" . $row->Size . "</td>"; 
               echo "<td><a href='records.php?ProductID=" . $row->ProductID . "'>Edit</a></td>"; 
               echo "<td><a href='delete.php?ProductID=" . $row->ProductID . "'>Delete</a></td>"; 
               echo "</tr>"; 
             } 
             echo "</table>"; 
           } 
           else 
           { 
             echo "No results to display!"; 
           } 
         } 
         else 
         { 
           echo "Error: " . $mysqli->error; 
         } 


         $mysqli->close(); 

       ?> 

Answer 1

你必須有一些數據庫類，檢查你的代碼。

$mysqli = new Database(); 
$mysqli->connect(); 

您執行查詢之前：

$result = $mysqli->query("SELECT ProductName, Description, Price, Size FROM Products ORDER BY ProductID"); 

正如你所看到的，查詢先走，然後連接資源。 >>所以，先連接。

Answer 2

您需要首先實例化$ mysqli的obect。你也沒有在任何地方打開數據庫。

你所需要的，至少，是這樣的：

$mysqli = new ClassName(/*some parameters here*/); 

$mysqli->database_open(/* some parameters here */); // or something like this, look at the clas definition