Question

<?php 
    $stmt = $con->prepare("SELECT id FROM sample WHERE  ID = (SELECT MAX(id)  FROM sample)");
    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);
    $result = $stmt->fetchAll();

    foreach ($result as $row2) {
        $auto1 = $row2['id'];

            if ($auto1 ===' ') {
                echo "There is no ID!";
            } else {
                echo $auto1; 
            }

    }
?>

如果数据库中有值，则会显示最大ID，但是如果我得到＆＃34的结果，我将删除所有数据以进行尝试; ID上没有ID！＆＃34;它没有显示..帮助我

Answer 1

当返回零行时，您当前的代码不会出现错误消息。您将获得此信息的行是：

$result = $stmt->fetchAll();

如果没有返回任何行，fetchAll()方法将返回FALSE，因此只需检查该值并相应地显示错误消息。

<?php 
    $stmt = $con->prepare("SELECT id FROM sample WHERE  ID = (SELECT MAX(id)  FROM sample)");
    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);
    $result = $stmt->fetchAll();


    if($!result){
        echo "No rows found..!";
    } else { 
        foreach ($result as $row2) {
            $auto1 = $row2['id'];

            if ($auto1 ===' ') {
                echo "There is no ID!";
            } else {
                echo $auto1; 
            }
        }
    }
?>

如果数据库表中没有值，如何在Php中显示

1 个答案: