如果條件滿足時條件不執行（條件：兩個變量都爲NULL）

Question

我正在運行兩個變量下拉查詢搜索，但似乎遇到if語句時遇到條件時不會執行的問題。特別是當兩個下拉列表位於缺省選定選項時，返回值爲NULL。

請參閱下面的代碼。

代碼爲兩個下拉列表：

print("<form action='patients.php' method='get'>"); 



// csSelection & sfSelection declaration of arrays to populate dropdown selection 
$csSelection=array("","","","",""); 
$sfSelection=array("","","","",""); 
if(isset($_REQUEST['search'])) { 

    if (isset($_GET['cs'])) { 
      $csSelection=array("","","","",""); 
      $cs= $_GET['cs']; 

      if ($cs=='1') {$csSelection[1]='selected';} 
      else if ($cs=='2') {$csSelection[2]='selected';} 
      else if ($cs=='3') {$csSelection[3]='selected';} 
      else if ($cs=='4') {$csSelection[4]='selected';} 
      else if ($cs=='0') {$csSelection[0]='selected';} 
      //var_dump($cs); 
      //var_dump($csSelection); 
    } 

    if (isset($_GET['sf'])) { 
      $sfSelection=array("","","","",""); 
      $sf = $_GET['sf']; 

      if ($sf=='Analyzed') {$sfSelection[1]='selected';} 
      else if ($sf=='New Case') {$sfSelection[2]='selected';} 
      else if ($sf=='Updated Case') {$sfSelection[3]='selected';} 
      else if ($sf=='None') {$sfSelection[4]='selected';} 
      else if ($sf=='0') {$sfSelection[0]='selected';} 
    } 
} 


// Case status dropdown list 
print("<select name='cs'> 
      <option ".$csSelection[0]." value=''>--Select Case Status--</option> 
      <option value='1' ".$csSelection[1].">Pass</option> 
      <option value='2' ".$csSelection[2].">Failed</option> 
      <option value='3' ".$csSelection[3].">Pass With Error</option> 
      <option value='4' ".$csSelection[4].">Indeterminate</option> 
     </select>"); 

// Case Flag dropdown list 
print("<select name='sf'> 
      <option ".$sfSelection[0]." value=''>--Select Flagged Status--</option> 
      <option value='Analyzed' ".$sfSelection[1].">Analyzed Case</option> 
      <option value='New Case' ".$sfSelection[2].">New Case</option> 
      <option value='Updated Case' ".$sfSelection[3].">Updated Case (New Images)</option> 
      <option value='None' ".$sfSelection[4].">No Status Flag</option> 
     </select>"); 

print("<input type='submit' name='search' value='Search'></form>"); 

如果語句。 else if (($cs==NULL) && ($sf==NULL))聲明有問題，它不返回任何內容。

if (isset($_GET['cs']) && isset($_GET['sf'])) { 
      $cs= $_GET['cs']; 
      $sf= $_GET['sf']; 

      var_dump($cs); 
      var_dump($sf); 

      if (($sf==NULL) && ($cs!==NULL)) { 
        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(DISTINCT caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID and sub_status_lookup.STATUS_ID = '".$cs."' 
        Group By patientid, cases.status";  

      } else if (($sf!==NULL) && ($cs==NULL)) { 
        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(DISTINCT caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID and cases.status_flag = '".$sf."' 
        Group By patientid, cases.status";  
        //var_dump($sql); 
      } else if (($cs!==NULL) && ($sf!==NULL)){ 

        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(DISTINCT caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID and sub_status_lookup.STATUS_ID = '".$cs."' and cases.status_flag = '".$sf."' 
        Group By patientid, cases.status";  

      } else if (($cs==NULL) && ($sf==NULL)) { 
        var_dump($sql); // This does not print out when both $cs and $sf are on the default NULL 

        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID 
        Group By patientid, cases.status "; 

      } 
} 

更新：感謝您的意見！我確實將最後一條語句從if（isset）條件移入else語句。但是，它仍然不起作用，我發現當兩者都爲NULL時，不要去else語句。它執行第一個if語句，條件爲：(($sf==NULL) && ($cs!==NULL)) $ cs和$ sf值從URL抓取：patients.php？cs = & sf = & search = Search。我該如何補救？

Answer 1

你的if語句的編寫方式(isset($_GET['cs']) && isset($_GET['sf'])必須是真的，甚至到達else if語句。

從邏輯上說，它們是相互顛倒的，所以你的最終if語句永遠不會運行。嘗試將$cf == null && $sf == null分支的內容移動到外部if的else子句中。

if (isset($_GET['cs']) && isset($_GET['sf'])) { 
      $cs= $_GET['cs']; 
      $sf= $_GET['sf']; 

      var_dump($cs); 
      var_dump($sf); 

      if (($sf==NULL) && ($cs!==NULL)) { 
        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(DISTINCT caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID and sub_status_lookup.STATUS_ID = '".$cs."' 
        Group By patientid, cases.status";  

      } else if (($sf!==NULL) && ($cs==NULL)) { 
        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(DISTINCT caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID and cases.status_flag = '".$sf."' 
        Group By patientid, cases.status";  
        //var_dump($sql); 
      } else if (($cs!==NULL) && ($sf!==NULL)){ 

        $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(DISTINCT caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
        Where cases.status = sub_status_lookup.SUB_ID and sub_status_lookup.STATUS_ID = '".$cs."' and cases.status_flag = '".$sf."' 
        Group By patientid, cases.status";  

      } 
} else { 
    var_dump($sql); // This does not print out when both $cs and $sf are on the default NULL 

    $sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup 
    Where cases.status = sub_status_lookup.SUB_ID 
    Group By patientid, cases.status "; 
}