我正在使用 PHP 和 MYSQL 构建一个简单的测验程序。
测验旨在一次显示一个问题;问题是选择题(每个问题有 4 个可能的答案)
如果玩家选择了正确的,他将继续下一个问题; 如果他选错了,测验就结束了。
起初,我设计的测验如下:
(1)创建了一个数据库表,其中包含1500个问题。该表包含以下列:
ID (primary key)
QUESTION (the question itself)
A1 (first answer)
A2 (second answer)
A3 (third answer)
A4 (fourth answer)
CORRECT (the correct answer --- which is one of the above A1 to A4)
(2) 然后,我的 PHP 代码被设计为按顺序(使用 ID 作为引用)一个接一个地挑选问题。
因此,当用户开始玩游戏时,他从问题 1 开始,然后是问题 2,依此类推。
(3) 为了让它更有趣,我在数据库中添加了一个额外的列 (begin_id),当用户在我的测验网站上注册为玩家时,它的默认值为“1”。每次用户回答问题时,此列都会更新为该问题的“ID”。意思是,它记录了用户回答的最后一个问题(无论是错误还是正确)。这样:下次用户登录并进行测验时,他不会从问题 1 开始。相反,他从列表中的下一个问题开始。 (意思是,用户永远不会看到同一个问题两次!)
代码如下:
// Query database
$get_question = "SELECT * from questions_table where id = $begin_id";
$result_get_question = mysqli_query($conn, $get_question);
$row_get_question = mysqli_fetch_array($result_get_question);
// Assign database response to variables
$question = $row_get_question['question'];
$a1 = $row_get_question['a1'];
$a2 = $row_get_question['a2'];
$a3 = $row_get_question['a3'];
$a4 = $row_get_question['a4'];
$correct = $row_get_question['correct'];
// Check user answer
if (isset($_POST['submit'])) {
$selected_radio = $_POST['response'];
if ($selected_radio == $correct)
echo "THAT ANSWER IS CORRECT";
else
echo "THAT ANSWER IS WRONG!";
}
而且,一切都很顺利!!
现在,我决定让它更“高效”;我没有按顺序选择问题,而是决定简单地修改我的 PHP-SELECT 语句,以随机选择问题。
这很容易,特别是因为有很多关于如何完成此操作的在线教程。
这是我使用的代码(最简单的):
SELECT * from questions_table order by rand() limit 1;
就选择随机问题而言,这是可行的。但是,出了点问题:无论用户选择什么答案,它始终是错误答案!!
出于某种原因,从数据库中选择随机问题打乱了我的 PHP 代码中的“正确答案/错误答案”逻辑。
不知道哪里出了问题。
更新
$get_question = "SELECT * from questions_table where id = $begin_id"; $result_get_question = mysqli_query($conn,$get_question); $row_get_question = mysqli_fetch_array($result_get_question); $question_id = $row_get_question['question_id']; $question = $row_get_question['question']; $a1 = $row_get_question['a1']; $a2 = $row_get_question['a2']; $a3 = $row_get_question['a3']; $a4 = $row_get_question['a4']; $correct = $row_get_question['correct'];
<br> <form method ="post" action =""> <input type="radio" name="response" value="<?=$a1?>"><?=$a1?><br> <input type="radio" name="response" value="<?=$a2?>"><?=$a2?><br> <input type="radio" name="response" value="<?=$a3?>"><?=$a3?><br> <input type="radio" name="response" value="<?=$a4?>"><?=$a4?><br> <input type="hidden" name="question_id" value="<?= echo $question_id?>" /> <br> <Input type = "submit" Name = "submit" Value = "Answer"> </form>
最佳答案
当您向用户提问时,系统会从数据库中随机选择一个问题。
然后,用户提交您的表单,随机选择另一个问题,这就是您用来检查答案的问题,而不是您向用户提出的问题。
您需要在您的表单中添加一个包含问题 ID 的隐藏输入
<input type="hidden" name="question_id" value="<?php echo $question_id ?>" />
然后当你检查答案时,一定要从数据库中获取正确的问题
代码看起来像这样
<?php
// Check user answer for previous question
if (isset($_POST['submit'])) {
// Retrieve the id of the question you asked
$previous_question_id = (int) $_POST['question_id']; // cast to integer to prevent sql injection.
// Query database
$get_question = "SELECT * from questions_table where id = $previous_question_id";
$result_get_question = mysqli_query($conn, $get_question);
$row_get_question = mysqli_fetch_array($result_get_question);
// Assign database response to variables
$correct = $row_get_question['correct'];
$selected_radio = $_POST['response'];
if ($selected_radio == $correct)
echo "THAT ANSWER IS CORRECT";
else
echo "THAT ANSWER IS WRONG!";
}
// Load new question to ask to the user
$get_question = "SELECT * from questions_table order by rand() limit 1";
$result_get_question = mysqli_query($conn,$get_question);
$row_get_question = mysqli_fetch_array($result_get_question);
// assign thing we want to print in the template to variable
$question_id = $row_get_question['question_id'];
$question = $row_get_question['question'];
$a1 = $row_get_question['a1'];
$a2 = $row_get_question['a2'];
$a3 = $row_get_question['a3'];
$a4 = $row_get_question['a4'];
?>
<PASTE YOUR TEMPLATE HERE>
关于php - 从 MySQL 数据库中选择随机问题; "correct answer"搞砸了,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31914891/