功能结构不遵循问题(PHP)

<?php


        PickModule(); // Show the thing to pick module

        if(ModuleIsSubmitted()) // When module is picked
        {
            PickSession(); // Show the thing to pick session
            if(SessionIsSubmitted()) // When session is picked
            {
              ShowAssessment(); // Show students and questions information
              if(StudentAnswersIsSubmitted()) // Student Answers button is submitted
                {
                  StudentAnswers();
                }

            }

        }



    ?>

我试图遵循这样的页面结构：

>显示PickModule()
>当用户在PickModule()函数中提交时,它将检入if(ModuleIsSubmitted())然后输出CheckSession()中的check结果
>显示PickSession()
>当用户在PickSession()函数中提交时,它将检查if(SessionIsSubmitted())然后输出ShowAssessment()中的check结果
>显示ShowAssessment()
>当用户在ShowAssessment()函数中提交时,它将检查if(StudentAnswersIsSubmitted())以检查是否单击了提交按钮,然后在StudentAnswers()中输出结果
>显示StudentAnswers()

我遇到的问题是最后两个要点,当单击answerSubmit按钮并在if(StudentAnswersIsSubmitted())中检查时,然后直接返回到PickModule(),而不是在StudentAnswers()中显示结果功能.我究竟做错了什么？

下面是通过每个函数的代码：

这是以下代码的演示：DEMO

function PickModule()
{ ?>
    <form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post"> 
        <?php            
        $moduleactive = 1;

        $sql = "SELECT ModuleId,ModuleNo,ModuleName FROM Module WHERE ModuleActive = ? ORDER BY ModuleNo"; 

        //mysqli code for modules drop down menu

        ?>
        <strong>Module:</strong>
        <select name="module" id="modulesDrop">
            <option value="">Please Select</option>
            <?php
            while($sqlstmt->fetch()) { 
                $ov = $dbModuleNo . "_" . $dbModuleName . "_" . $dbModuleId; 
                if(isset($_POST["module"]) && $ov == $_POST["module"]) 
                    echo "<option selected='selected' value='$ov'>$dbModuleNo - $dbModuleName</option>" . PHP_EOL; 
                else 
                    echo "<option value='$ov'>$dbModuleNo - $dbModuleName</option>" . PHP_EOL;
             } 
            ?>
        </select>
        <br>
        <input id="moduleSubmit" type="submit" value="Submit Module" name="moduleSubmit" />
    </form>
<?php }
function ModuleIsSubmitted()
{
    if(isset($_POST["module"]) && empty($_POST["module"])) // We picked the "Please select" option
    { ?>
            Please Select a Module
    <?php 
        return false;
    }
    else if(!isset($_POST["module"]))
    {
        return false;
    }
    else // All is ok
    {
        return true;
    }
    return false;
}
function PickSession()
{

    $dataTransfered = explode( "_",$_POST["module"] );
    $moduleNo = $dataTransfered[0];
    $moduleName = $dataTransfered[1];
    $moduleId = $dataTransfered[2];

    //Get data from database
    $sessionquery = "
        SELECT s.SessionId,SessionName,SessionDate,SessionTime,ModuleId,SessionActive,Complete
        FROM Session s
        INNER JOIN Session_Complete sc ON sc.SessionId = s.SessionId
        WHERE
        (ModuleId = ? AND Complete = ?)
        ORDER BY SessionName 
        ";
    $complete = 1;

//mysqli code for assessments drop down menu  

    ?>

    <form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post"> 
        <input type="hidden" name="module" value="<?php echo $_POST['module']; ?>">
        <p>
            <strong>Selected Module: </strong><?php echo $moduleNo ." - ". $moduleName; ?> 
        </p>
    <?php if ($sessionnum == 0 ){ ?>
        <div class="red">
            Sorry,You have No Assessments under this Module
        </div>
    <?php } else { ?>
           <p>
        <strong>Asessments:</strong>
        <select name="session" id="sessionsDrop">
            <option value="">Please Select</option>
            <?php
                while ( $sessionqrystmt->fetch() ) {
                    $sv = $dbSessionId;
                    if($dbSessionActive == 0){
                        $class = 'red';
                    }else{
                        $class = 'green';   
                    }
                    if(isset($_POST["session"]) && $sv == $_POST["session"]) 
                        echo "<option selected='selected' value='$sv' class='$class'>" . $dbSessionName . " - " . date('d-m-Y',strtotime($dbSessionDate)) . " - " . date('H:i',strtotime($dbSessionTime)) . "</option>" . PHP_EOL;
                    else
                        echo "<option value='$sv' class='$class'>" . $dbSessionName . " - " . date('d-m-Y',strtotime($dbSessionTime)) . "</option>" . PHP_EOL;
                }
            ?>
        </select>
        </p>
        <input id="sessionSubmit" type="submit" value="Submit Assessments" name="sessionSubmit" />
    </form>
<?php
}
}
function SessionIsSubmitted()
{
        if(isset($_POST["session"]) && empty($_POST["session"])) // We picked the "Please select" option
        { ?>
            <div class="red">
                Please Select an Assessment
            </div>
        <?php 
            return false;
        }
    else if(!isset($_POST["session"]))
    {
        return false;
    }
    else // All is ok
    {
        return true;
    }
    return false;

}


function ShowAssessment()
{   

$studentactive = 1;

$currentstudentqry = "
SELECT
st.StudentId,st.StudentAlias,st.StudentForename,st.StudentSurname
FROM
Student_Session ss 
INNER JOIN
Student st ON ss.StudentId = st.StudentId
WHERE
(ss.SessionId = ? AND st.Active = ?)
ORDER BY st.StudentAlias
";

//mysqli code for students drop down menu


if($studentnum == 0){ ?>

<div class="red">
There are no Students who have currently taken this Assessment
</div>
<?php } else { 

$questionsqry = "
SELECT
QuestionId,QuestionNo
FROM
Question
WHERE
(SessionId = ?)
ORDER BY QuestionNo
";

//mysqli code for questions drop down menu

        ?>

<form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">         
<p>
<input type="text" name="session" value="<?php echo $_POST['session']; ?>">
<strong>Student:</strong>
<select name="student" id="studentsDrop">
<option value="All">All</option>
<?php
while ( $currentstudentstmt->fetch() ) {
$stu = $dbStudentId;
if(isset($_POST["student"]) && $stu == $_POST["student"]) 
    echo "<option selected='selected' value='$stu'>" . $dbStudentAlias . " - " . $dbStudentForename . " " . $dbStudentSurname . "</option>" . PHP_EOL;
else
    echo "<option value='$stu'>" . $dbStudentAlias . " - " . $dbStudentForename . " " . $dbStudentSurname . "</option>" . PHP_EOL;
}
?>
</select>
</p>

<p>
<strong>Question:</strong>
<select name="question" id="questionsDrop">
<option value="All">All</option>
<?php
while ( $questionsstmt->fetch() ) {
$ques = $dbQuestionId;
if(isset($_POST["question"]) && $ques == $_POST["question"]) 
    echo "<option selected='selected' value='$ques'>" . $dbQuestionNo . "</option>" . PHP_EOL;
else
    echo "<option value='$ques'>" . $dbQuestionNo . "</option>" . PHP_EOL;
}
?>
</select>
</p>

<input id="answerSubmit" type="submit" value="Get Student's Answers" name="answerSubmit" />
</form>

<?php
}
}

function StudentAnswersIsSubmitted()
{

if(!isset($_POST["answerSubmit"]))
    {
        return false;
    }
    else // All is ok
    {
        return true;
    }
    return false;

}

function StudentAnswers()
{

echo "student answers";

}

?>