需要有關MySQL查詢的幫助

Question

前三個查詢工作正常，但最后一個則不能。 第二個查詢可以正常使用$status !== ''但最后一個查詢具有相同的$status !== ''沒有執行查詢，任何人都可以幫我$status !== ''

if (isset($_POST['go'])) {

     $status = $_POST[status];
     if ($status == 4){
             $status = '' ;
     }

    if ($topic == 100 && $subtopic == '' && $status == '' ) {
    $queryString = "select * from tblquiz where userid='$_SESSION[numericuserid]' LIMIT $start, $limit" ;
    $countString = "select * from tblquiz where userid='$_SESSION[numericuserid]'";
    }  // NOTE : THIS QUERY IS WORKING PERFECT

       elseif ($topic !== '' && $subtopic !== '' && $status !== '' ) {
    $queryString = "select * from tblquiz where qstatus=$status AND  qtopic='$topic[topicname]' AND subtopic='$_POST[subtopic]' AND userid='$_SESSION[numericuserid]' LIMIT $start, $limit" ;
    $countString = "select * from tblquiz where qstatus=$status AND  qtopic='$topic[topicname]' AND subtopic='$_POST[subtopic]' AND      userid='$_SESSION[numericuserid]'";
       }  // NOTE : THIS QUERY IS WORKING PERFECT

       elseif ($topic !== '' && $subtopic !== '' && $status == '' ) {
    $queryString = "select * from tblquiz where   qtopic='$topic[topicname]' AND subtopic='$_POST[subtopic]' AND userid='$_SESSION[numericuserid]' LIMIT $start, $limit" ;
    $countString = "select * from tblquiz where   qtopic='$topic[topicname]' AND subtopic='$_POST[subtopic]' AND userid='$_SESSION[numericuserid]'";
       }  // NOTE : THIS QUERY IS WORKING PERFECT


       elseif  ($topic == 100 && $subtopic == '' && $status !== '') {
    $queryString = "select * from tblquiz where qstatus= $status AND userid='$_SESSION[numericuserid]' LIMIT $start, $limit" ;
    $countString = "select * from tblquiz where qstatus= $status AND userid='$_SESSION[numericuserid]' ";
     }  **// NOTE : THIS QUERY IS NOT WORKING** 

}

Answer 1

select * from tblquiz where qstatus= '$status' 

qstatus缺少引號嗎？

Answer 2

在您的elseif子句中，檢查$ status為空，然后將其設置為$ querystring和$ countstring。 這意味着您嘗試查詢

qstatus= AND

這應該會產生一個SQL錯誤。 嘗試調試時，打印出sql語句始終是一個好主意。