Question

我有一个已定义的数组。如果是列中的一个（例如Bayern'by'）为空，那么我没有收到变量 $ row_wohn_by ，并且在结果之后得到的是：注意：未定义的变量：row_wohn_by < / p>

简单擦除不是另一种操作的解决方案。预期定义为 $ row_wohn_by ， 0 （零）数字。

这是代码：

$states = array(
    'Baden-Württemberg' => 'bw',
    'Bayern' => 'by',
    'Berlin' => 'be',
    'Thüringen' => 'th'
    );

    $numb_rows = mysqli_query($conn, 'SELECT COUNT(*)
                                        FROM members
                                        WHERE priv_staat = "Deutschland"
                                        ');
        $numb_row = mysqli_fetch_array($numb_rows);
        $total_wohn = $numb_row[0];

    $query_wohn = mysqli_query($conn, "SELECT `priv_land`, COUNT(*) AS `count` FROM `members` WHERE `priv_land` !=0 GROUP BY `priv_land`");
        while ($item_wohn = $query_wohn->fetch_assoc()) {
            ${'row_wohn_'.$states[$item_wohn['priv_land']]} = $item_wohn['count'];
            ${'row_wohn_per_'.$states[$item_wohn['priv_land']]} = number_format((($item_wohn['count'] / $total_wohn)*100), 2, ',', ' '); // calulate in %
    }

    $row_wohn_all = $total_wohn-($row_wohn_bw + $row_wohn_by + $row_wohn_be + $row_wohn_th);
    $row_wohn_per_all = number_format((($row_wohn_all / $total_wohn)*100), 2, ',', ' ');  // calulate in %

感谢您的帮助。

Answer 1

您写道：

预期定义 $ row_wohn_by 0

查看您的查询（SELECT priv_land, COUNT(*) AS count FROM members），只有当没有行与priv_land = 'by'时才会出现这种情况。因此，在查询之后的while循环中，该变量永远不会被设置。

解决方案：使用值0初始化所有变量，并使用查询结果覆盖那些变量：

foreach($states as $privLand) {
    ${'row_wohn_' . $privLand} = 0;
    ${'row_wohn_per_' . $privLand} = 0;
}

$query_wohn = mysqli_query($conn, "SELECT `priv_land`, COUNT(*) AS `count` FROM `members` WHERE `priv_land` !=0 GROUP BY `priv_land`");
while ($item_wohn = $query_wohn->fetch_assoc()) {
    ${'row_wohn_'.$states[$item_wohn['priv_land']]} = $item_wohn['count'];
    ${'row_wohn_per_'.$states[$item_wohn['priv_land']]} = number_format((($item_wohn['count'] / $total_wohn)*100), 2, ',', ' '); // calulate in %
}

对于奖励积分，将所有内容重写为数组 - 通知会使生活变得更轻松（仅适用于$row_wohn_*）：

// Initialize all keys with value 0
$row_wohn = array_fill_keys($states, 0);

$query_wohn = mysqli_query($conn, "SELECT `priv_land`, COUNT(*) AS `count` FROM `members` WHERE `priv_land` !=0 GROUP BY `priv_land`");
while ($item_wohn = $query_wohn->fetch_assoc()) {
    $row_wohn[ $states[$item_wohn['priv_land']] ] = $item_wohn['count'];
}

$row_wohn_all = $total_wohn - array_sum( $row_whon );

如果变量从数组获得结果，则为未定义的变量

1 个答案: