Question

我正在使用phpMyadmin和innoDb引擎。我已经完成了插入和删除。但我不能更新任何东西。我无法理解错误。我从updatestudent.php调用了updatestudent。转到函数updatestudent但它返回错误并且更新不成功。

updateStudent.php

require_once '../includes/DbOperations.php';

$response = array(); 

if($_SERVER['REQUEST_METHOD']=='POST'){
    if(isset($_POST['name']) and isset($_POST['mobileno']) and isset($_POST['sem']) and isset($_POST['section']) and isset($_POST['usn'])){
        $db = new DbOperations(); 

        if($db->updateStudent($_POST['mobileno'], $_POST['sem'], $_POST['section'], $_POST['usn'])){
            $user = $db->getStudentByUsername($_POST['name']);
            $response['error'] = false; 
            $response['name'] = $user['name'];
            $response['email'] = $user['email'];
            $response['mobileno'] = $user['mobileno'];
            $response['dept'] = $user['dept'];
            $response['sem'] = $user['sem'];
            $response['usn'] = $user['usn'];
            $response['section']=$user['section'];
        }else{
            $response['error'] = true; 
            $response['message'] = "Update was not successful";         
        }

    }else{
        $response['error'] = true; 
        $response['message'] = "Required fields are missing";
    }
}

echo json_encode($response);

updateStudent函数

public function updateStudent($mobileno, $sem, $section, $usn){
            $stmt = $this->con->prepare("UPDATE `student` SET mobileno = ? AND sem = ? AND section = ? WHERE usn = ? ");
            $stmt->bind_param("ssss",$mobileno, $sem, $section, $usn);
            $stmt->execute();
            return $stmt->get_result();

        }

Answer 1

你的sql语句不正确：

UPDATE `student` SET mobileno = ? AND sem = ? AND section = ? WHERE usn = ?

应该是

UPDATE `student` SET mobileno = ? , sem = ?, section = ? WHERE usn = ?

Answer 2

return $stmt->get_result();不是判断UPDATE是否成功的正确方法。 mysqli_stmt::get_result()的文档说：

返回成功SELECT查询的结果集，或其他DML查询或失败时返回FALSE。 mysqli_errno（）函数可用于区分两种类型的失败。

因此，对于UPDATE查询，它始终会返回FALSE。您需要致电mysqli_errno()以确定它是否真的成功：

return $this->conn->errno == 0;

您还需要更正UPDATE查询的语法，它应该是：

UPDATE `student` SET mobileno = ? , sem = ?, section = ? WHERE usn = ?

由于查询的语法不正确，prepare()失败，因此$stmt为FALSE，当您致电$stmt->bind_param()时，您应该收到错误。

无法在InnoDb中更新数据库

2 个答案: