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php - 使用 ORDER BY 子句通过使用从下拉菜单中选择的值来对查询进行排序

转载 作者:行者123 更新时间:2023-11-29 04:54:41 25 4
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我想使用下拉列表来排序查询结果。无论在下拉列表中选择什么选项,查询都将按所选选项升序排列。我的查询工作正常,我只需要包含我知道在 WHERE 子句之后的 ORDER BY 子句。请仔细查看表格,请帮我解决这个问题。

代码如下:

    <!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>

<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" /></p> <!-- Enter Session Id here-->
<p>Module Number: <input type="text" name="moduleid" /></p> <!-- Enter Module Id here-->
<p>Teacher Username: <input type="text" name="teacherid" /></p> <!-- Enter Teacher here-->
<p>Student Username: <input type="text" name="studentid" /></p> <!-- Enter User Id here-->
<p>Grade: <input type="text" name="grade" /></p> <!-- Enter Grade here-->
<p>Order Results By: <select name="order">
<option name="noorder">Don't Order Results</option>
<option name="ordersessionid">Session ID</option>
<option name="ordermoduleid">Module Number</option>
<option name="orderteacherid">Teacher Username</option>
<option name="orderstudentid">Student Username</option>
<option name="ordergrade">Grade</option>
</select>
<p><input type="submit" value="Submit" /></p>
</form>

<?php

$username="xxx";
$password="xxx";
$database="mobile_app";

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

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

$sessionid = $_POST['sessionid'];
$moduleid = $_POST['moduleid'];
$teacherid = $_POST['teacherid'];
$studentid = $_POST['studentid'];
$grade = $_POST['grade'];

$result = mysql_query("SELECT * FROM Module m INNER JOIN Session s ON m.ModuleId = s.ModuleId JOIN Grade_Report gr ON s.SessionId = gr.SessionId JOIN Student st ON gr.StudentId = st.StudentId WHERE ('$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')");

$num=mysql_numrows($result);

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>

我曾尝试使用友情发布给我的 switch 语句,但我无法让它工作。这是我在下面尝试做的:

$orderfield = isset ($_POST['order']);
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");

我们将不胜感激任何帮助。谢谢你

最佳答案

尝试

$orderfield = isset ($_POST['order']) ? $_POST['order'] : 'default order field';

参见 http://php.net/manual/en/function.isset.php

更新

刚刚注意到...ORDER BY 语句的参数不是参数而是表达式。换句话说,在查询中丢失 $orderfield 周围的单引号,即

... ORDER BY $orderfield ASC");

关于php - 使用 ORDER BY 子句通过使用从下拉菜单中选择的值来对查询进行排序,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/7762314/

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