PHP致命錯誤：調用一個成員函數bind_param（）

我已經看了這個劇本好像是30倍，我不能爲我的生活找到我的問題。下面是代碼：PHP致命錯誤：調用一個成員函數bind_param（）

function redeem() { 

     $case = $_POST["case"]; 
     $name = $_POST["name"]; 
     $profession = $_POST["profession"]; 
     $city = $_POST["city"]; 
     $country = $_POST["country"]; 
     $totalpercent = $_POST["totalpercent"]; 
     $pretest = $_POST["pretest"]; 
     $posttest = $_POST["posttest"]; 
     $investigationspercent = $_POST["investigationspercent"]; 
     $timesreset = $_POST["timesreset"]; 
     $creditsspent = $_POST["creditsspent"]; 
     $timescompleted = $_POST["timescompleted"]; 

     //Add the information to the learnent_cases_leaderboard table 
     $stmt = $this->db->prepare("INSERT INTO learnent_cases_leaderboard (case, name, profession, city, country, totalpercent, pretest, posttest, investigationspercent, creditsspent, timescompleted, timesreset, timestamp) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, CURRENT_TIMESTAMP)"); 

     $stmt->bind_param("sssssiiiiiii", $case, $name, $profession, $city, $country, $totalpercent, $pretest, $posttest, $investigationspercent, $creditsspent, $timescompleted, $timesreset); //the quotations specify the type of variable; 
     //See http://php.net/manual/en/mysqli-stmt.bind-param.php for more information on bind_param 
     $stmt->execute(); 
     $stmt->close();

當我看到錯誤日誌，它給了我這個錯誤消息：

105號線這條線：

PHP Fatal error: Call to a member function bind_param() on a non-object on line 105

代碼：

$stmt->bind_param("sssssiiiiiii", $case, $name, $profession, $city, $country, $totalpercent, $pretest, $posttest, $investigationspercent, $creditsspent, $timescompleted, $timesreset);

來源

2011-08-07 Scott Kohlert

也許我與我的PHP太生疏，但我認爲我們需要看到$這個 - >分貝聲明。這聽起來像$ this-> db-> prepare並不實際返回一個對象。 – Kris

可能的重複[參考 - 這個錯誤在PHP中意味着什麼？]（http://stackoverflow.com/questions/12769982/reference-what-does-this-error-mean-in-php） –