php页面传值接接不到值解决方案

php页面传值接接不到值
当前页面为tp.php 有一个form表单要传值给当前页面，

当点击之后地址栏的确出现了传值内容 但是当前页面的语句却接不到值

请教各位高人帮忙看看是怎么回事

PHP code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
                       $sql = 'select * from phone';
        
            if(isset($_GET['yy'])){
                echo "hjfkgljfdfffffffffffffff";//经测试 没有输出，即没有接到值
                $screen=$_GET["screen"];
                $moshi=$_GET["moshi"];
                $system=$_GET["system"];
                $xilie=$_GET["xilie"];
                if ($moshi !='0'){
                    if(strpos($sql,'where'))
                        $sql.=' and `p_moshi`='.$moshi;
                    else
                        $sql.=' where `p_moshi`='.$moshi;
                }
                if ($screen!='0'){
                    if(strpos($sql,'where'))
                    $sql.=' and `p_screen`='.$screen;
                    else
                        $sql.=' where `p_screen`='.$screen;
                }
                if ($system!='0'){
                    if(strpos($sql,'where'))
                    $sql.=' and `p_system`='.$system;
                    else
                        $sql.=' where `p_system`='.$system;
                }
                if ($xilie!='0'){
                    if(strpos($sql,'where'))
                    $sql.=' and `p_xilie`='.$xilie;
                    else
                        $sql.=' where `p_xilie`='.$xilie;
                }
            }
            
            
                    echo $sql.'<br>';

로그인 후 복사

HTML code

<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->

로그인 후 복사