如何对两个循环使用一个查询

Question

how can i write query in this situation: this is the query

$gdQuery = $conn->query("blah blah ");

i want to use the above query for while loop that is two time.

1. is to retrive skillname (name)
2. is to retrivestudent name (student_fname)

is it a correct approach if not how can i do that..?

<table>
<thead>
    <th>Paricipant</th> 
    <?php while($gdData = $gdQuery->fetch_assoc()) {  ?> 
    <th class="text-center"><?php echo $gdData['name']; ?></th> <?php } ?> 
    <th>Score</th> 
</thead>
<tbody>
    <tr>
        <?php while($gdData = $gdQuery->fetch_assoc()) {    ?>
        <td><?php echo  $gdData['student_fname']; ?></td> <?php }   ?> 
        <td style="line-height:45px">Score</td> 
    </tbody> 
</table>

My problem is when i write this the second while loop is not working

Answer 1

fetch_assoc retrieves one row from query result. You can use it until you run out of rows in that result set. By calling it multiple times you are moving towards the end of result set. That is reason why there is nothing to do for second while loop. RTD http://php.net/manual/en/mysqli-result.fetch-assoc.php

Use fetch_all to get all rows before you start iterating and store them in variable. Use that variable for your iterations.

Alternatively you may try to use data_seek to reset pointer in result set to beginning after first while loop. http://php.net/manual/en/mysqli-result.data-seek.php