如何基于另一个表的ID从表中获取行数

Question

So I have an index.php page that spits out data from two tables on my database. The first table, questions contains one column for my QuestionID and looks like this:

qid
----
 1
 2
 3

The second table called answers contains two columns, one for my AnswersID and the other which links to my QuestionsID on the questions table, and it looks like this:

aid | aqid
----|-----
 1  |  3
 2  |  1
 3  |  1

So on my index.php page, I basically want to echo out every qid row from the questions table and beside it the total number of answers ( aid rows from the answers table) corresponding to each QuestionID . To put simply, the result I want achieved on my index.php page is this:

QuestionID: 1 / Answers: 2
QuestionID: 2 / Answers: 0
QuestionID: 3 / Answers: 1

But based on my current code I am having trouble achieving this result. It keeps echoing out the wrong number of rows for each table. This is the unwanted result I am getting:

QuestionID: 1 / Answers: 3
QuestionID: 2 / Answers: 3
QuestionID: 3 / Answers: 3

So how would I fix this to achieve the correct result? This is my current code:

<?php 
$sql = "
SELECT questions.*, GROUP_CONCAT(answers.aqid) AS aqid
FROM questions 
LEFT JOIN answers
ON questions.qid=answers.aqid
GROUP BY questions.qid
";
$result = $conn->query($sql);
while($row = $result->fetch_assoc()) {
    $qid = $row["qid"];
    $aqid = $row["aqid"];
    $row_cnt = $result->num_rows;
?>
<div>
    QuestionID: <?php echo $qid; ?>
    <?php foreach($answers as $answer): ?>
        Answers: <?php echo $row_cnt; ?>
    <?php endforeach; ?>
</div>
<?php } ?>

Thank you for your help.

Answer 1

group_concat() returns a concatenated string. You might be looking for count() .

Also, count() returns a row count.
There doesn't seem to be a need for $row_cnt or the foreach .

Here's an example:

$sql = "
    SELECT
        q.`qid`,
        COUNT(a.`aqid`) AS `answerCount`
    FROM `questions` q
    LEFT JOIN `answers` a
        ON a.`aqid` = q.`qid`
    GROUP BY q.`qid`
    ";

$result = $conn->query($sql);

while($row = $result->fetch_assoc()) {
    ?>
    <div>
      QuestionID: <?php echo $row["qid"]; ?>
      Answers: <?php echo $row["answerCount"]; ?>
    <div>
    <?php
}
?>