您应该明确地加入，但据我了解，您想要的是出价计数?在这种情况下，您应该进行分组查询，类似于ilias所说的，但是:

you should definently make a join, but from what I understand what you want is the bid-count? In that case you should make a group-by query, similar to what ilias is saying, but:

$query->select('count(itemBids.bids) AS bidsNum');
$query->join('LEFT', '#__entrusters_bids AS itemBids ON itemBids.item_id = a.id');
$query->group('a.id'); 

还要注意联接中on语句中的引用更改，

also notice to the reference change in the on-statement in the join,

向乔纳斯致敬