可能重复：
How can I get drop down menu value still selected after form is submitted?
当我在文本框中输入数据并提交表单时，数据仍然存储在文本框中，这很好。例如我使用过。我现在要做的是，当从下拉菜单中选择一个值并提交表单时，我希望所选的值仍然显示为下拉列表中的选定值，但我无法做到这一点。有什么想法吗？
以下是代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Exam Interface</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<?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);
?>
<p><strong>NOTE: </strong>If a search box is left blank, then the form will search for all data under that specific field</p>
<form action="exam_interface.php" method="post" name="sessionform"> <!-- This will post the form to its own page"-->
<p>Session ID: <input type="text" name="sessionid" value="<?PHP print $sessionid ; ?>" /></p> <!-- Enter Session Id here-->
<p>Module Number: <input type="text" name="moduleid" value="<?PHP print $moduleid ; ?>" /></p> <!-- Enter Module Id here-->
<p>Teacher Username: <input type="text" name="teacherid" value="<?PHP print $teacherid ; ?>" /></p> <!-- Enter Teacher here-->
<p>Student Username: <input type="text" name="studentid" value="<?PHP print $studentid ; ?>" /></p> <!-- Enter User Id here-->
<p>Grade: <input type="text" name="grade" value="<?PHP print $grade ; ?>" /></p> <!-- Enter Grade here-->
<p>Order Results By: <select name="order" value="<?PHP print $orderfield ; ?>">
<option value="ordersessionid">Session ID</option>
<option value="ordermoduleid">Module Number</option>
<option value="orderteacherid">Teacher Username</option>
<option value="orderstudentid">Student Username</option>
<option value="ordergrade">Grade</option>
</select>
<p><input type="submit" value="Submit" name="submit" /></p>
</form>
<?php
$username="u0867587";
$password="31may90";
$database="mobile_app";
mysql_connect('localhost',$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);
if(isset($_POST['submit'])) {
switch ($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;
}
$result = mysql_query("SELECT * FROM Module m INNER JOIN Session s ON m.ModuleId = s.ModuleId JOIN Grade_Report gr ON s.SessionId = gr.SessionId JOIN Student st ON gr.StudentId = st.StudentId WHERE ('$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 $orderfield ASC");
$num=mysql_numrows($result);
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'"; echo ", <strong>Order Results By:</strong>";if ($orderfield == 'gr.SessionId') echo " 'Session ID'"; else if ($orderfield == 'm.ModuleId') echo " 'Module Number' "; else if ($orderfield == 's.TeacherId') echo " 'Teacher Username' "; else if ($orderfield == 'gr.StudentId') echo " 'Student Username' "; else if ($orderfield == 'gr.Grade') echo " 'Grade' ";"</p>";
echo "<p>Number of Records Shown in Result of the Search: <strong>$num</strong></p>";
echo "<table border='1'>
<tr>
<th>Student Id</th>
<th>Forename</th>
<th>Session Id</th>
<th>Grade</th>
<th>Mark</th>
<th>Module</th>
<th>Teacher</th>
</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();
?>
</body>
</html>
谢谢
答案 0 :(得分：0)
<p>Order Results By: <select name="order" value="<?PHP print $orderfield ; ?>">
<option value="ordersessionid" <?php echo ($_POST['name'] == 'ordersessionid') ? 'selected="true"' : ''; ?>>Session ID</option>
<option value="ordermoduleid" <?php echo ($_POST['name'] == 'ordermoduleid') ? 'selected="true"' : ''; ?>>Module Number</option>
<option value="orderteacherid" <?php echo ($_POST['name'] == 'orderteacherid') ? 'selected="true"' : ''; ?>>Teacher Username</option>
<option value="orderstudentid" <?php echo ($_POST['name'] == 'orderstudentid') ? 'selected="true"' : ''; ?>>Student Username</option>
<option value="ordergrade" <?php echo ($_POST['name'] == 'ordergrade') ? 'selected="true"' : ''; ?>>Grade</option>
</select>
答案 1 :(得分：0)
以下是我的页面版本，提及的修改太多了。如果你什么都不懂，请随意问......
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Exam Interface</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<?php
$username="xxx";
$password="xxx";
$database="mobile_app";
mysql_connect('localhost',$username,$password);
@mysql_select_db($database) or die("Unable to select database");
foreach (array('sessionid','moduleid','teacherid','studentid','grade','orderfield') as $varname) {
$$varname = (isset($_POST[$varname])) ? $_POST[$varname] : '';
}
switch ($orderfield) {
case 'ordersessionid':
$orderfield = 'gr.SessionId';
$ordername = 'Session ID';
break;
case 'ordermoduleid':
$orderfield = 'm.ModuleId';
$ordername = 'Module Number';
break;
case 'orderteacherid':
$orderfield = 's.TeacherId';
$ordername = 'Teacher Username';
break;
case 'orderstudentid':
$orderfield = 'gr.StudentId';
$ordername = 'Student Username';
break;
case 'ordergrade':
default:
$orderfield = 'gr.Grade';
$ordername = 'Grade';
break;
}
?>
<p><strong>NOTE: </strong>If a search box is left blank, then the form will search for all data under that specific field</p>
<form action="exam_interface.php" method="post" name="sessionform"> <!-- This will post the form to its own page"-->
<p>Session ID: <input type="text" name="sessionid" value="<?php echo $sessionid; ?>" /></p> <!-- Enter Session Id here-->
<p>Module Number: <input type="text" name="moduleid" value="<?php echo $moduleid; ?>" /></p> <!-- Enter Module Id here-->
<p>Teacher Username: <input type="text" name="teacherid" value="<?php echo $teacherid; ?>" /></p> <!-- Enter Teacher here-->
<p>Student Username: <input type="text" name="studentid" value="<?php echo $studentid; ?>" /></p> <!-- Enter User Id here-->
<p>Grade: <input type="text" name="grade" value="<?php echo $grade; ?>" /></p> <!-- Enter Grade here-->
<p>Order Results By:
<select name="orderfield">
<option value="ordersessionid"<?php if ($orderfield == 'ordersessionid') echo ' selected="selected"' ?>>Session ID</option>
<option value="ordermoduleid"<?php if ($orderfield == 'ordermoduleid') echo ' selected="selected"' ?>>Module Number</option>
<option value="orderteacherid"<?php if ($orderfield == 'orderteacherid') echo ' selected="selected"' ?>>Teacher Username</option>
<option value="orderstudentid"<?php if ($orderfield == 'orderstudentid') echo ' selected="selected"' ?>>Student Username</option>
<option value="ordergrade"<?php if ($orderfield == 'ordergrade') echo ' selected="selected"' ?>>Grade</option>
</select>
</p>
<p><input type="submit" value="Submit" name="submit" /></p>
</form>
<?php
if (isset($_POST['submit'])) {
$query = "
SELECT * FROM Module m
INNER JOIN Session s ON m.ModuleId = s.ModuleId
JOIN Grade_Report gr ON s.SessionId = gr.SessionId
JOIN Student st ON gr.StudentId = st.StudentId
WHERE
('".mysql_real_escape_string($sessionid)."' = '' OR gr.SessionId = '".mysql_real_escape_string($sessionid)."')
AND
('".mysql_real_escape_string($moduleid)."' = '' OR m.ModuleId = '".mysql_real_escape_string($moduleid)."')
AND
('".mysql_real_escape_string($teacherid)."' = '' OR s.TeacherId = '".mysql_real_escape_string($teacherid)."')
AND
('".mysql_real_escape_string($studentid)."' = '' OR gr.StudentId = '".mysql_real_escape_string($studentid)."')
AND
('".mysql_real_escape_string($grade)."' = '' OR gr.Grade = '".mysql_real_escape_string($grade)."')
ORDER BY $orderfield ASC";
$num = mysql_num_rows($result = mysql_query($query));
mysql_close();
?>
<p>
Your Search:
<strong>Session ID:</strong> <?php echo (empty($sessionid)) ? "'All Sessions'" : "'$sessionid'"; ?>,
<strong>Module ID:</strong> <?php echo (empty($moduleid)) ? "'All Modules'" : "'$moduleid'"; ?>,
<strong>Teacher Username:</strong> <?php echo (empty($teacherid)) ? "'All Teachers'" : "'$teacherid'"; ?>,
<strong>Student Username:</strong> <?php echo (empty($studentid)) ? "'All Students'" : "'$studentid'"; ?>,
<strong>Grade:</strong> <?php echo (empty($grade)) ? "'All Grades'" : "'$grade'"; ?>,
<strong>Order Results By:</strong> '<?php echo $ordername; ?>'
</p>
<p>Number of Records Shown in Result of the Search: <strong><?php echo $num ?></strong></p>
<table border='1'>
<tr>
<th>Student Id</th>
<th>Forename</th>
<th>Session Id</th>
<th>Grade</th>
<th>Mark</th>
<th>Module</th>
<th>Teacher</th>
</tr>
<?php
while ($row = mysql_fetch_array($result)) {
echo "
<tr>
<td>{$row['StudentId']}</td>
<td>{$row['Forename']}</td>
<td>{$row['SessionId']}</td>
<td>{$row['Grade']}</td>
<td>{$row['Mark']}</td>
<td>{$row['ModuleName']}</td>
<td>{$row['TeacherId']}</td>
</tr>";
}
?>
</table>
<?php
}
?>
</body>
</html>