如何在php上循环变量

Question

i have problem on my comment list in my forum website php please help i trying to looping all the user comment, but it just appear 1 or fail looping that show all same comment in many number.

<?php
include 'connection.php'; 
        echo '<table border="1" bgcolor="#FBFBEF" width="100%" height="20"><tr>';
        echo '<td width="80%" height="20"><strong>Thread :';
        $query="select title from topic where topic_id=".$_REQUEST['topic'];
        $result=mysql_query($query);
        $row=mysql_fetch_array($result);
        echo $row['title'];
    if($row){
      do{   
    echo'</strong></td><td  align="center" valign="top"><strong><?php ';
      $query2="select * from comment where topic_id=".$_REQUEST['topic'];
      $result2=mysql_query($query2);
      $row2=mysql_fetch_array($result2);
      echo $row2['post_date'];
      echo '</strong></td></tr></table>';
    echo '<table border="1" bgcolor="#FBFBEF" width="100%" height="20"><tr><td align="center" valign="top" height="20"><strong> Post By :<strong></td><td width="85%" ><strong>';
        echo $row['title'];
        echo'</strong></td></tr>';
    echo '<tr><td align="center" valign="top"><strong>';
            $query3="select * from user_login where email='".$row2['post_by_user']."'";
            $result3=mysql_query($query3);
            $row3=mysql_fetch_array($result3);
            echo '<br>'.$row3['first_name'].' '.$row3['last_name'];

        echo '</strong></td><td align="left" valign="top" height=200>';
      //displaying list comment
    echo '<p>'.$row2['description'].'</p><hr>';
     }while($row=mysql_fetch_array($result2));
      }
      ?>
        </td>
    </tr>

why is the looping failed ?

Answer 1

I have re-arranged your loop. The first thing wrong was while($row=mysql_fetch_array($result2)) because you are using $row2 in that loop and changing $row won't help.

<?php
include 'connection.php';
echo '<table border="1" bgcolor="#FBFBEF" width="100%" height="20"><tr>';
echo '<td width="80%" height="20"><strong>Thread :';
$query = "select title from topic where topic_id=" . $_REQUEST['topic'];
$result = mysql_query($query);
$row = mysql_fetch_array($result);
echo $row['title'];
if ($row) {
    echo '</strong></td><td  align="center" valign="top"><strong><?php ';
    $query2 = "select * from comment where topic_id=" . $_REQUEST['topic'];
    $result2 = mysql_query($query2);
    while ($row2 = mysql_fetch_array($result2)) {
        echo $row2['post_date'];
        echo '</strong></td></tr></table>';
        echo '<table border="1" bgcolor="#FBFBEF" width="100%" height="20"><tr><td align="center" valign="top" height="20"><strong> Post By :<strong></td><td width="85%" ><strong>';
        echo $row['title'];
        echo '</strong></td></tr>';
        echo '<tr><td align="center" valign="top"><strong>';
        $query3 = "select * from user_login where email='" . $row2['post_by_user'] . "'";
        $result3 = mysql_query($query3);
        $row3 = mysql_fetch_array($result3);
        echo '<br>' . $row3['first_name'] . ' ' . $row3['last_name'];

        echo '</strong></td><td align="left" valign="top" height=200>';
        //displaying list comment
        echo '<p>' . $row2['description'] . '</p><hr>';
    }
}
?>
</td>
</tr>

Very Important: You are highly prone to SQL-Injection. Please at-least sanitize your input before feeding to SQL. Also you are using depreciated mysql_* functions. Instead, use the MySQLi or PDO_MySQL extension.

Side note: errors are inversely proportional to readability of your code. and maintainability is proportional to square of readability.

Edit: If you want echo $row2['post_date'] only once for the loop you can use the loop like this. This will print post_date of the first row only.

if ($row) {
    echo '</strong></td><td  align="center" valign="top"><strong><?php ';
    $query2 = "select * from comment where topic_id=" . $_REQUEST['topic'];
    $result2 = mysql_query($query2);
    $row2 = mysql_fetch_array($result2);
    if ($row2) {
        echo $row2['post_date'];
        do {
            echo '</strong></td></tr></table>';
            echo '<table border="1" bgcolor="#FBFBEF" width="100%" height="20"><tr><td align="center" valign="top" height="20"><strong> Post By :<strong></td><td width="85%" ><strong>';
            echo $row['title'];
            echo '</strong></td></tr>';
            echo '<tr><td align="center" valign="top"><strong>';
            $query3 = "select * from user_login where email='" . $row2['post_by_user'] . "'";
            $result3 = mysql_query($query3);
            $row3 = mysql_fetch_array($result3);
            echo '<br>' . $row3['first_name'] . ' ' . $row3['last_name'];

            echo '</strong></td><td align="left" valign="top" height=200>';
            //displaying list comment
            echo '<p>' . $row2['description'] . '</p><hr>';
        } while($row2 = mysql_fetch_array($result2));
    }
}