想要删除数据库中的名称 n 它必须显示该名称是否存在[关闭]答案

【问题标题】：want to delete a name in database n it must display if the name exists or not [closed]想要删除数据库中的名称 n 它必须显示该名称是否存在[关闭]
【发布时间】：2016-04-20 09:47:44
【问题描述】：

<?php
    $hostname = "localhost";

    $username = "ODBC";

    $password = "";

    $dbname = "db_students";

    try{
        $dbh = new PDO("mysql:host=$hostname;dbname=$dbname",$username,$password);

        echo"Connected to database"."<br/>";

        $dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);

        $stmt = $dbh->prepare("DELETE FROM enrolments
                WHERE student_name = :name");

        $stmt->bindParam(":name",$name,PDO::PARAM_STR,255);

        $name = "Pietie Kock";
        $stmt->execute();

        if($student_name > 0)
        {
           echo "record deleted ". $student_name;
        }else{

           echo "record doesn't exist". $student_name;

            $dbh = null;
            }catch(PDOException $e){
            echo $e->getMessage();
            }
        ?>

【问题讨论】：

你应该添加至少一个问题，以及你的一些问题描述。
现在是它的格式，下次我上传问题时我会这样做

标签： php pdo

【解决方案1】：

$student_name 在您的代码中未定义要检查受最后一条 SQL 语句影响的行数，我们使用 rowCount()

$stmt->execute();
if ($stmt->rowCount > 0) {
        echo "record deleted " . $student_name;
    } else {

        echo "record doesn't exist" . $student_name;

        $dbh = null;
    }

你也忘了关闭try你的代码是

try {
    $dbh = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password);

    echo"Connected to database" . "<br/>";

    $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $stmt = $dbh->prepare("DELETE FROM enrolments
                WHERE student_name = :name");

    $stmt->bindParam(":name", $name, PDO::PARAM_STR, 255);

    $name = "Pietie Kock";
    $stmt->execute();


    if ($stmt->rowCount > 0) {
        echo "record deleted " . $student_name;
    } else {

        echo "record doesn't exist" . $student_name;

        $dbh = null;
    }
} catch (PDOException $e) {// close you try
    echo $e->getMessage();
}

【讨论】：