我如何以及在哪里放置我的 header() 以便我的 if else 条件可以运行多次？

Question

我有一个系统供用户申请许可证......当他们 select 他们希望退休时，我的系统应该能够检查是否符合标准或者他们之前是否已经申请过该许可证以防止垃圾邮件。

但是，我有一个大问题。 如果我把header('Location:s_success.php'); 警报不会出现。 例如，因为用户可以选择 1 个或 2 个或更多许可，.

设想

假设选择一个他们有资格申请的许可证和另一个他们还没有资格申请的许可证。

预期结果

在这种情况下，应该发生的是系统应该将他们带到成功页面，同时提醒他们他们没有资格获得的其他许可没有成功。

但意想不到的结果：

他们系统只是 go 到成功页面，而没有警告用户不合格的许可不成功。

这是我的代码：

<?php
session_start();
include'Connections/database.php';
$conn = dbConnect ();
    if (! $conn)
    die("Couldn't connect to MySQL");
    
    $user = $_SESSION['eid'];
    $selectedPermit=$_POST['cat'];
    $_SESSION['selectedPermit']=$selectedPermit;
    
    foreach($selectedPermit as $permit)
    {
        $query="SELECT t.PREREQ1, t.PREREQ2, (CASE WHEN (t.PREREQ1 IS NOT NULL) AND (p1.PTYPE IS NULL) THEN 1 ELSE 0 END) AS missing1, (CASE WHEN (t.PREREQ2 IS NOT NULL) AND (p2.PTYPE IS NULL) THEN 1 ELSE 0 END) AS missing2 FROM type AS t LEFT JOIN permit AS p1 ON (t.PREREQ1=p1.ptype) AND ( p1.EID = '$user' ) AND (p1.STATUS='approved') LEFT JOIN permit AS p2 ON (t.PREREQ2=p2.ptype) AND ( p2.EID = '$user' ) AND (p2.STATUS='approved') WHERE t.PTYPE = '$permit' ";
        $result=mysql_query($query,$conn);
        $row=mysql_fetch_assoc($result);
        $missing1=$row['missing1'];
        $missing2=$row['missing2'];
        
        if($missing1=='1' or $missing2=='1')
        {
            $message='You have not met the pre-requisites for '. $permit .' \n';
//              echo "You did have not met the Pre-Requisites for." .$permit;
            echo "<script>alert(\"$message\");";
//              header('Location:s_apply2.php');
            echo "location.href='s_apply2.php';</script>";
        }
        elseif($missing1 =='0' and $missing2 =='0')
        {
            $query="SELECT PTYPE FROM permit WHERE EID='$user'";
            $result=mysql_query($query);
            
            if(mysql_num_rows($result)==0)
            {
                $query="SELECT MED FROM emp WHERE EID='$user'";
                    $result=mysql_query($query);
                    $row=mysql_fetch_assoc($result);
                    $med=$row['MED'];
                
                    if($med == 'yes')
                    {
//                          echo "You are Fine.";
                        $query = "INSERT INTO permit (EID, PTYPE) VALUES ('$user','$permit' )";
                        mysql_query($query);
                        header('Location:s_apply_success.php');
                    }
                    else
                    {
//                          echo "Go do Medical form";
                        header('Location:medical_question.php');
                    }
            }
            else
            {
                while($row=mysql_fetch_assoc($result))
                {
                    $appliedPermit[]=$row['PTYPE'];
                }
            
                if(in_array($permit,$appliedPermit))
                {
                        $message1='You have already applied '. $permit .' before. \n';
//                          echo"You have already applied for ".$permit ." before <br/>";
                        echo "<script>alert(\"$message1\");";
//                          header('Location:s_apply2.php');
                        echo "location.href='s_apply2.php';</script>";
                }
                else
                {
                    $query="SELECT MED FROM emp WHERE EID='$user'";
                    $result=mysql_query($query);
                    $row=mysql_fetch_assoc($result);
                    $med=$row['MED'];
                
                    if($med == 'yes')
                    {
                    //  echo "You are Fine.";
                        $query = "INSERT INTO permit (EID, PTYPE) VALUES ('$user','$permit' )";
                        mysql_query($query);
                        header('Location:s_apply_success.php');
                    }
                    else
                    {
                        echo "Go do Medical form";
                    //  header('Location:medical_question.php');
                    }
                }
            }
        }
    }
    
    dbDisconnect($conn);
  
?>

疑似错误：

在我的代码中，我怀疑是因为我正在使用header('Location:s_apply_success.php'); 因此导致意想不到的结果发生。 但我无法确认这是不是错误。

我试图做些什么来调试可疑的错误：

但我确实尝试使用echo "You are Fine."; 而不是header('Location:s_apply_success.php'); 它有效。 它确实有回声和弹出窗口。

Answer 1

来自 PHP 手册：

http://php.net/manual/en/function.header.php

请记住，必须在发送任何实际的 output 之前调用 header()，无论是通过正常的 HTML 标记、文件中的空行，还是来自 PHP。使用 include、require、函数或其他函数读取代码是一个非常常见的错误文件访问 function，并且在调用 header() 之前有空格或空行 output。 使用单个 PHP/HTML 文件时也存在同样的问题。

Answer 2

总结一下，在header()之前不能显示或显示任何东西，给下一页传递一个消息。

Answer 3

Output 缓冲将补偿您在调用header()之前对 output 的回显：

<?php
session_start();
ob_start();
include'Connections/database.php';
$conn = dbConnect ();
    if (! $conn)
    die("Couldn't connect to MySQL");

    $user = $_SESSION['eid'];
    $selectedPermit=$_POST['cat'];
    $_SESSION['selectedPermit']=$selectedPermit;

    foreach($selectedPermit as $permit)
    {
        $query="SELECT t.PREREQ1, t.PREREQ2, (CASE WHEN (t.PREREQ1 IS NOT NULL) AND (p1.PTYPE IS NULL) THEN 1 ELSE 0 END) AS missing1, (CASE WHEN (t.PREREQ2 IS NOT NULL) AND (p2.PTYPE IS NULL) THEN 1 ELSE 0 END) AS missing2 FROM type AS t LEFT JOIN permit AS p1 ON (t.PREREQ1=p1.ptype) AND ( p1.EID = '$user' ) AND (p1.STATUS='approved') LEFT JOIN permit AS p2 ON (t.PREREQ2=p2.ptype) AND ( p2.EID = '$user' ) AND (p2.STATUS='approved') WHERE t.PTYPE = '$permit' ";
        $result=mysql_query($query,$conn);
        $row=mysql_fetch_assoc($result);
        $missing1=$row['missing1'];
        $missing2=$row['missing2'];

        if($missing1=='1' or $missing2=='1')
        {
            $message='You have not met the pre-requisites for '. $permit .' \n';
//              echo "You did have not met the Pre-Requisites for." .$permit;
            echo "<script>alert(\"$message\");";
//              header('Location:s_apply2.php');
            echo "location.href='s_apply2.php';</script>";
        }
        elseif($missing1 =='0' and $missing2 =='0')
        {
            $query="SELECT PTYPE FROM permit WHERE EID='$user'";
            $result=mysql_query($query);

            if(mysql_num_rows($result)==0)
            {
                $query="SELECT MED FROM emp WHERE EID='$user'";
                    $result=mysql_query($query);
                    $row=mysql_fetch_assoc($result);
                    $med=$row['MED'];

                    if($med == 'yes')
                    {
//                          echo "You are Fine.";
                        $query = "INSERT INTO permit (EID, PTYPE) VALUES ('$user','$permit' )";
                        mysql_query($query);
                        header('Location:s_apply_success.php');
                    }
                    else
                    {
//                          echo "Go do Medical form";
                        header('Location:medical_question.php');
                    }
            }
            else
            {
                while($row=mysql_fetch_assoc($result))
                {
                    $appliedPermit[]=$row['PTYPE'];
                }

                if(in_array($permit,$appliedPermit))
                {
                        $message1='You have already applied '. $permit .' before. \n';
//                          echo"You have already applied for ".$permit ." before <br/>";
                        echo "<script>alert(\"$message1\");";
//                          header('Location:s_apply2.php');
                        echo "location.href='s_apply2.php';</script>";
                }
                else
                {
                    $query="SELECT MED FROM emp WHERE EID='$user'";
                    $result=mysql_query($query);
                    $row=mysql_fetch_assoc($result);
                    $med=$row['MED'];

                    if($med == 'yes')
                    {
                    //  echo "You are Fine.";
                        $query = "INSERT INTO permit (EID, PTYPE) VALUES ('$user','$permit' )";
                        mysql_query($query);
                        header('Location:s_apply_success.php');
                    }
                    else
                    {
                        echo "Go do Medical form";
                    //  header('Location:medical_question.php');
                    }
                }
            }
        }
    }

    dbDisconnect($conn);
    ob_end_flush();
?>