Why is my `if(isset($_POST['submit']))` Not Hiding the Echo and Table on Page Load?

Why if(isset($_POST['submit'])) is Not Working to Hide Echos and Table on Page Load

Problem Description

The if(isset($_POST['submit'])) statement is intended to hide specified echos and a table when the script is initially opened. However, after implementing this code, users report that the echos and table are still visible even after the submit button is clicked.

Solution

The issue arises because the submit button is not assigned a unique name in the code provided. To remedy this, the button should be given a name, as seen in the corrected code below:

<p><input type="submit" value="Submit" name="submit" /></p>

With this modification, the if(isset($_POST['submit'])) statement will correctly detect when the submit button has been clicked and perform the intended actions to hide the desired elements.

Moreover, the original code missed the database connectivity codes that connect to the database. For better understanding, the corrected and complete code is as follows:

<?php
$username = "xxx";
$password = "xxx";
$database = "mobile_app";

mysql_connect('localhost', $username, $password);

@mysql_select_db($database) or die("Unable to select database");

$sessionid = isset($_POST['sessionid']) ? $_POST['sessionid'] : "";
$moduleid = isset($_POST['moduleid']) ? $_POST['moduleid'] : "";
$teacherid = isset($_POST['teacherid']) ? $_POST['teacherid'] : "";
$studentid = isset($_POST['studentid']) ? $_POST['studentid'] : "";
$grade = isset($_POST['grade']) ? $_POST['grade'] : "";
$orderfield = isset($_POST['order']) ? $_POST['order'] : "";

$sessionid = mysql_real_escape_string($sessionid);
$moduleid = mysql_real_escape_string($moduleid);
$teacherid = mysql_real_escape_string($teacherid);
$studentid = mysql_real_escape_string($studentid);
$grade = mysql_real_escape_string($grade);

switch ($orderfield) {
    case 'ordersessionid':
        $orderfield = 'gr.SessionId';
        break;
    case 'ordermoduleid':
        $orderfield = 'm.ModuleId';
        break;
    case 'orderteacherid':
        $orderfield = 's.TeacherId';
        break;
    case 'orderstudentid':
        $orderfield = 'gr.StudentId';
        break;
    case 'ordergrade':
        $orderfield = 'gr.Grade';
        break;
}

$ordertable = $orderfield;

$result = mysql_query("SELECT * FROM Module m INNER JOIN Session s ON m.ModuleId = s.ModuleId JOIN Grade_Report gr ON s.SessionId = gr.SessionId JOIN Student st ON gr.StudentId = st.StudentId WHERE ('$sessionid' = '' OR gr.SessionId = '$sessionid') AND ('$moduleid' = '' OR m.ModuleId = '$moduleid') AND ('$teacherid' = '' OR s.TeacherId = '$teacherid') AND ('$studentid' = '' OR gr.StudentId = '$studentid') AND ('$grade' = '' OR gr.Grade = '$grade') ORDER BY $ordertable ASC");

$num = mysql_numrows($result);

if (isset($_POST['submit'])) {
    echo "<p>Your Search: <strong>Session ID:</strong> ";
    if (empty($sessionid)) echo "'All Sessions'";
    else echo "'$sessionid'";
    echo ", <strong>Module ID:</strong> ";
    if (empty($moduleid)) echo "'All Modules'";
    else echo "'$moduleid'";
    echo ", <strong>Teacher Username:</strong> ";
    if (empty($teacherid)) echo "'All Teachers'";
    else echo "'$teacherid'";
    echo ", <strong>Student Username:</strong> ";
    if (empty($studentid)) echo "'All Students'";
    else echo "'$studentid'";
    echo ", <strong>Grade:</strong> ";
    if (empty($grade)) echo "'All Grades'";
    else echo "'$grade'";
    "</p>";

    echo "<p>Number of Records Shown in Result of the Search: <strong>$num</strong></p>";

    echo "<table border='1'>";
    echo "<tr>";
    echo "<th>Student Id</th>";
    echo "<th>Forename</th>";
    echo "<th>Session Id</th>";
    echo "<th>Grade</th>";
    echo "<th>Mark</th>";
    echo "<th>Module</th>";
    echo "<th>Teacher</th>";
    echo "</tr>";
    while ($row = mysql_fetch_array($result)) {
        echo "<tr>";
        echo "<td>" . $row['StudentId'] . "</td>";
        echo "<td>" . $row['Forename'] . "</td>";
        echo "<td>" . $row['SessionId'] . "</td>";
        echo "<td>" . $row['Grade'] . "</td>";
        echo "<td>" . $row['Mark'] . "</td>";
        echo "<td>" . $row['ModuleName'] . "</td>";
        echo "<td>" . $row['TeacherId'] . "</td>";
        echo "</tr>";
    }
    echo "</table>";
}

mysql_close();
?>

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