PHP if-then-else语句不起作用

Question

我的网址是这样的:"inventory.php？sorting = 1"等等.页面加载正常,但不能正确显示信息.

mysql_connect("localhost","user","pass"); 
mysql_select_db("database"); 

if ($sorting == 1){
$result = mysql_query("select * from vehicles ORDER BY year DSC");
}
elseif ($sorting == 2){
$result = mysql_query("select * from vehicles ORDER BY make DSC");
}
elseif ($sorting == 3){
$result = mysql_query("select * from vehicles ORDER BY miles DSC");
}
elseif ($sorting == 4){
$result = mysql_query("select * from vehicles ORDER BY downpay DSC");
}
elseif ($sorting == 5){
$result = mysql_query("select * from vehicles ORDER BY pricepay DSC");
}
elseif ($sorting == 6){
$result = mysql_query("select * from vehicles ORDER BY pricecash DSC");
}
else {
$result = mysql_query("select * from vehicles");
}

while($r=mysql_fetch_array($result))

Answer 1

为什么不直接使用字段名作为GET变量？

$sortField = $_GET['sorting'];
// Ensure we don't get any SQL injection:
$validFields = array('year', 'make', 'miles' ... 'pricecash');


$sql = "select * from vehicles";

if(in_array($sortField, $validFields)){
    $sql .= ' ORDER BY ' . $sortField .' DESC';
}

mysql_query($sql);

然后使用inventory.php？sorting = year等访问该页面.

这使得URL更具可读性,可预测性并且意味着您可以通过将新字段添加到阵列来支持新字段,而无需编写新的开关案例.

Answer 2

您需要更换$sorting与$_GET["sorting"]

但是也:

使用该switch声明不是更好的主意吗？

switch($_GET["sorting"]{
    case 1:
    $result = mysql_query("select * from vehicles ORDER BY year DSC");
    break;
case 2:

等等