Question

如此处所示，如果存在与$ member_id匹配的数字ID，则该记录将被删除且$ res的计算结果为TRUE。如果表中包含＆＃39; member_id＆＃39;这是一个像abc1234这样的字符串，只有在我将$ member_id作为一个字符串包含在引号中时才会删除＆＃39; $ member_id＆＃39;将删除所有匹配，但是当$ res总是评估为TRUE时，如果不匹配，则不会删除任何内容（应该如此），但用户会获得＆＃34; $ member_id。＆＃34;已从会员表中删除＆＃34;信息。我希望这很清楚。

<?php 
$member_id = "";
require("connect.php");
if (isset($_POST['member_id']))$member_id = fix_string($_POST['member_id']);

$sql=("DELETE FROM members WHERE member_id = $member_id");
$res = mysqli_query($con,$sql);
**if($res) {
 echo "member with ID of ".$member_id." has been removed from members table";
} else {
    echo "member was not deleted";
}**

function fix_string($string) {
    if (get_magic_quotes_gpc()) $string = stripslashes($string);
    return htmlentities ($string);
}
?>

Answer 1

您的逻辑位于正确的位置，但未正确执行。您正在尝试通过执行以下操作来查看是否已删除用户/成员：

$res = mysqli_query($con,$sql);
if($res) {

但是，如果语句针对true正确执行，mysqli_query()将返回DELETE - 它是否删除行无关紧要。

您要做的是利用mysqli::$affected_rows：

$res = mysqli_query($con, $sql);
if (mysqli_affected_rows($con) == 1) {
    echo "member with ID of ".$member_id." has been removed from members table";
} else {
    echo "member was not deleted";
}

这将检查是否有一条受DELETE语句影响的记录（假设您的成员ID是唯一的;如果不是，则可以使用>= 1代替）。如果有一个，那么它就被删除了！

旁注（不具体回答）
您应该放弃fix_string()方法并选择mysqli准备好的语句，这些语句会为您自动清理输入。您可以针对现有代码尝试以下操作：

require("connect.php");
$member_id = (!empty($_POST['member_id']) ? $_POST['member_id'] : '');

// prepare the statement
$stmt = mysqli_prepare($con, 'DELETE FROM members WHERE member_id = ?');

// bind the id
mysqli_stmt_bind_param($stmt, "s", $member_id);

// execute the statement
mysqli_stmt_execute($stmt);

if (mysqli_affected_rows($con) == 1) {
    echo "member with ID of ".$member_id." has been removed from members table";
} else {
    echo "member was not deleted";
}

涉及字符串的查询结果始终计算为TRUE

1 个答案: