以下是一个简单的PHP星座查询系统的实例，它通过用户的出生日期来查询对应的星座。

```php

// 星座查询系统

// 星座日期范围

$zodiacs = [

'摩羯座' => ['12/22', '01/19'],

'水瓶座' => ['01/20', '02/18'],

'双鱼座' => ['02/19', '03/20'],

'白羊座' => ['03/21', '04/19'],

'金牛座' => ['04/20', '05/20'],

'双子座' => ['05/21', '06/20'],

'巨蟹座' => ['06/21', '07/22'],

'狮子座' => ['07/23', '08/22'],

'处女座' => ['08/23', '09/22'],

'天秤座' => ['09/23', '10/22'],

'天蝎座' => ['10/23', '11/21'],

'射手座' => ['11/22', '12/21']

];

// 获取用户输入的出生日期

$birthMonth = isset($_GET['month']) ? $_GET['month'] : '';

$birthDay = isset($_GET['day']) ? $_GET['day'] : '';

// 判断日期并输出星座

function findZodiac($month, $day) {

global $zodiacs;

foreach ($zodiacs as $zodiac => $dateRange) {

$start = $dateRange[0];

$end = $dateRange[1];

if (($month == $start[0] && $day >= $start[1]) || ($month == $end[0] && $day <= $end[1])) {

return $zodiac;

}

}

return '未知星座';

}

// 如果用户输入了日期，则进行查询

if ($birthMonth && $birthDay) {

$zodiac = findZodiac($birthMonth, $birthDay);

echo "