php在一个查询中从两个表打印结果

Question

i fetch two table result in one query. now i have in each table one row with name = userid . when i print id of table one, this not worked and printed id of table two . in ie i select * from product and then voteid,userid form voteproduct where userid = $userid ; now i need print userid from product table but my result print userid from voteproduct . how to fix this ? thanks

my code :

$sql = 'SELECT * FROM ' . PREFIX  . '_product,' . PREFIX  . '_voteproduct WHERE ' . PREFIX  . '_voteproduct.voteid = ' . PREFIX  . '_product.id AND ' . PREFIX  . '_voteproduct.userid =  "' . $userid . '" ORDER BY name ' . $pages->limit .' ';

    $db->query($sql) or error ('ERROR', mysql_error ());
          $result = $db->query ( $sql ); 
          if($db->numrows($result)>0){ 
          while ($row = $db->fetcharray($result))
       {

    echo $row['userid']; // PROBELM THIS PRINTED USERID FROM VOTEPRODUCT I NEED PRINT USER ID FROM PRODUCT
       }

EDIT : If I selected * from my product table, realy i need to all. ( name, price, date, category, ...)

Answer 1

select * is a lazy way of doing thigns, especially when it looks like you're only asking for a SINGLE field. You don't run to the store, grab the entire store's shelf stock, take it home, then throw away EVERYTHING except the one candy bar you wanted.

How about

SELECT product.userid
FROM ...
WHERE ...

so you get only the exact single field you need?

Answer 2

You can select each userid with AS in order to use them separately like below

$sql = 'SELECT p.userid as pid, vp.userid as vpid, ... FROM ' . PREFIX  . '_product AS p,' . PREFIX  . '_voteproduct AS vp WHERE vp.voteid = p.id AND vp.userid =  "' . $userid . '" ORDER BY name ' . $pages->limit .' ';

And use ;

echo $row['pid'];

Answer 3

select p.userid as puserid, v.userid as vuserid ... FROM ' . PREFIX  . '_product p,' . PREFIX  . '_voteproduct v where ...

echo $row['puserid'];