Question

for ($i=1;$i<5;$i++) //Loop read & save all vars from fieldform
{
    if (array_key_exists('country'.$i, $_POST) == true)
    {
            ${"country".$i} = $_POST['country'.$i];

            $get_id = mysqli_query($connection, "SELECT country_id FROM country WHERE country_pl = '{$country[$i]}'");
            $row = mysqli_fetch_assoc($get_id);
            $country_id = $row['country_id'];
            echo $country_id; 
    }
}

这是一个读取和循环的循环保存在表单字段中选择的国家/地区除了MYSQL QUERY之外，一切正常。我不知道如何在MySQL语句中正确编写'{$country[$i]}'。

Answer 1

不要使用变量变量，使用数组。

$country[$i] = mysqli_real_escape_string($connection, $_POST['country'.$i]);

然后你可以这样做：

$get_id = mysqlil_query($connection, "SELECT country_id FROM country WHERE country_pl = '{$country[$i]}'");

Answer 2

最好每次迭代运行一个查询而不是一个查询。我建议：

$countries = array();
for ($i=1;$i<5;$i++) //Loop read & save all vars from fieldform
{
    if (array_key_exists('country'.$i, $_POST))
    {
        $countries[] = mysqli_real_escape_string($connection, $_POST['country'.$i]);
    }
}

$get_id = mysqli_query($connection, "SELECT country_id FROM country WHERE country_pl IN ('" . implode ("', '", $countries) . "')");

while ($row = mysqli_fetch_assoc($get_id)) {
    $country_id = $row['country_id'];
    echo $country_id;
}

理想情况下，您应该使用预先准备好的声明，但这有点棘手：请参阅Trouble binding an imploded array into a mysql prepared statement

MYSQL SELECT语句，带有基于PHP循环的变量

2 个答案: