PHP post 提交 SQL 语句的值

Question

所以我尝试根据单击的提交按钮对 SQL 查询进行排序

我的排序选项:

echo "<form method='post' action adminview.php'>"
    ."<input type='submit' name='sort' value='Sort by Attempt ID'/><br />"
    ."<input type='submit' name='sort' value='Sort by Student ID'/><br />"
    ."<input type='submit' name='sort' value='Sort by lowest Score'/><br />"
    ."<input type='submit' name='sort' value='Sort by highest Score'/><br />"
    ."</form>";

当页面重新加载时，这里是检查单击了哪个按钮的代码

switch($_POST['sort'])
{
    case "Sort by Attempt ID":
        $sortby = "attempt_id";
        break;
    case "Sort by Student ID":
        $sortby = "student_id";
        break;
    case "Sort by lowest Score":
        $sortby = "score";
        break;
    case "Sort by highest Score":
        $sortby = "score desc";
        break;
}

我的问题是，当页面重新加载时，它说排序未定义。

如果你好奇的话，这里是 SQL 语句

$sqlstring = "select * from quizattempts order by '$sortby'";

Answer 1

单引号阻止对 $sortby 进行求值。只需删除它们即可:

$sqlstring = "select * from quizattempts order by $sortby";