我正在运行两个变量下拉查询搜索，但似乎遇到if-statement在满足条件时不执行的问题。特别是当两个下拉列表位于默认选定选项上时，返回值为NULL。
请参阅以下代码。
两个下拉列表的代码：
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' ".$sfSelection[4].">No Status Flag</option>
</select>");
print("<input type='submit' name='search' value='Search'></form>");
如果声明。对else if (($cs==NULL) && ($sf==NULL))语句有问题，它没有返回任何内容。
if (isset($_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
$sql = "SELECT patientid, sub_status_lookup.CASE_STATUS, sub_status_lookup.SUB_STATUS, count(caseid) as cases_count, cases.comments, date_mod, caseid, user_mod, status_flag FROM cases, sub_status_lookup
Where cases.status = sub_status_lookup.SUB_ID
Group By patientid, cases.status ";
}
}
更新：感谢您的评论！我确实将最后一个语句从if（isset）条件移到了else语句中。但是，它仍然无法正常工作，我发现当两者都为NULL时，而不是转到else语句。它在以下条件下执行第一个if语句：(($sf==NULL) && ($cs!==NULL))从URL中获取$ cs和$ sf值：patients.php？cs =＆amp; sf =＆amp; search = Search。我该如何解决这个问题？
答案 0 :(得分：2)
创建if语句的方式(isset($_GET['cs']) && isset($_GET['sf'])必须是真的，甚至可以使用else if语句。
从逻辑上讲，它们是彼此相反的，所以你的最后一个if语句永远不会运行。尝试将$cf == null && $sf == null分支的内容移动到外部if的else子句。
if (isset($_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 ";
}