MySQL查询未正确显示所有记录

Question

The query am running against my database to get the 3 records order it by Random. The problem is that sometimes it shows all 3 records sometimes it only shows 2, 1 and other times its just blank. In the database I have around 28 records.

What I have tried

1. I have tried without LIMIT - Problem Same
2. I have echoed out $suggested_profile_id found all 3 records coming out.

This is the query that gets the records LIMIT it by 3

<?php
$sql = "SELECT * FROM members WHERE member_status='activated' ORDER BY RAND() DESC LIMIT 3";
  $query = $db->SELECT($sql);
   if($db->NUM_ROWS() > 0){
     $rows = $db->FETCH_OBJECT();
?>

This is the code that runs and gets all 3 records in a loop.

<!-- Suggested Friends -->
    <div class="col-md-0 media-body">
    <?php
    foreach($rows as $row){
        $member_id = $row->member_id;
        $sql = "SELECT * FROM profile WHERE profile_id='$member_id' LIMIT 1";
        $query = $db->SELECT($sql);
        $rows = $db->FETCH_OBJECT();
        foreach($rows as $row){
            $suggested_profile_id = $row->profile_id;
            $suggested_profile_photo = $row->profile_photo;
            $suggested_profile_username = $row->profile_username;
            $suggested_profile_name = $row->profile_name;
                if(
                    $suggested_profile_id != GET_SESSION_ID_VALUE(ENCRYPTION_KEY)&&
                    !is_in_ARRAY($make_string_to_ARRAY, $suggested_profile_id) 
                ){
    ?>
    <div class="row margin0">
      <div class="col-md-4 pad0">
        <a href="/<?php echo $suggested_profile_username; ?>" title="<?php echo $suggested_friends_profile_name; ?>" >
        <?php
          global $suggested_friends_profile_id;
          $member_dir = dirname(dirname(dirname(__FILE__))) . "/members/" . $suggested_profile_id ."/smalll_" . $suggested_profile_photo;
          if(file_exists($member_dir)){
        ?>
          <img alt="<?php echo $suggested_profile_name; ?>" title="<?php echo $suggested_profile_name; ?>" src="/members/<?php echo $suggested_profile_id; ?>/smalll_<?php echo $suggested_profile_photo; ?>" width="50" height="50">
        <?php   
          } else {
        ?>
          <img alt="<?php echo $suggested_profile_name; ?>" title="<?php echo $suggested_profile_name; ?>" src="/assets/images/default.jpg" width="50" height="50">
        <?php   
          }
        ?>
        </a>
      </div>
      <div class="col-md-8 pad0">
        <a href="<?php echo $suggested_profile_username; ?>" class="bold welcome-name"><?php echo $suggested_profile_name; ?></a>
        <span class="f12 gray">271 Mutual Friends</span>
        <a href="#" class="welcome-name">Add as friend</a>
     </div>
    </div>
    <?php
                }
            }           
    }
    ?>
    </div>
    <!-- ** Suggested Friends -->

What am I missing? Is there any alternative way I can achieve this...thanks!

Answer 1

It looks to me like you're overwriting your $rows variable within the inner select.

foreach($rows as $row){ // <-- first $rows / $row
    $member_id = $row->member_id;
    $sql = "SELECT * FROM profile WHERE profile_id='$member_id' LIMIT 1";
    $query = $db->SELECT($sql);
    $rows = $db->FETCH_OBJECT(); <-- $rows overwritten
    foreach($rows as $row){ 

Break your display from your application logic and you won't have such a hard time debugging this kind of thing. Besides, you have a lot of duplicated code and that makes things hard to manage as well as being hard to debug.

Further, you wouldn't have this problem if you ran one query: SELECT * FROM members JOIN profile ON members.member_id = profile.profile_id and not only does your code get simpler and your double-foreach loop problem disappear, but your database access will also be a lot more efficient.