yii 两表联合查询有bug? [ 1.1 版本 ]

使用yii做一个练习，
对carInfo和goodsInfo两个表做联合查询，使用如下代码：

//两表查询，查同一客户(同样的userId)买的所有商品
$connection = Yii::app()->db;
$sql="select * from carInfo a inner join goodsInfo b on a.goodsId=b.goodsId where userId={$userId}";
$command = $connection->createCommand($sql);
$re = $command->queryAll();

查出的结果中bookCount字段始终为零，查出的结果如下：

array(1) {
  [0]=>
  array(15) {
    ["carId"]=>
    string(1) "1"
    ["userId"]=>
    string(1) "1"
    ["goodsNum"]=>
    string(7) "BJB0001"
    ["goodsId"]=>
    string(1) "6"
    ["bookCount"]=>
    string(1) "0"
    ["carTime"]=>
    string(19) "2016-10-29 20:04:49"
    ["typeId"]=>
    string(2) "18"
    ["goodsName"]=>
    string(15) "联想笔记本"
    ["brandId"]=>
    string(1) "6"
    ["price"]=>
    string(4) "3999"
    ["salePrice"]=>
    string(4) "3900"
    ["intro"]=>
    string(51) "该产品品质优良，是目前最流行的产品"
    ["spec"]=>
    string(11) "666-888-999"
    ["img1"]=>
    string(48) "images/201001/goods_img/4710_G_1262426233567.jpg"
    ["img2"]=>
    string(48) "images/201001/goods_img/4710_P_1262426233036.jpg"
  }
}

可以看到上面结果中其它字段都没问题，只有bookCount字段是0（与数据库结果不符），而在命令行状态查询carInfo表，结果是：

mysql> select * from carInfo;
+-------+--------+----------+---------+-----------+---------------------+
| carId | userId | goodsNum | goodsId | bookCount | carTime             |
+-------+--------+----------+---------+-----------+---------------------+
|     1 |      1 | BJB0001  |       6 |         2 | 2016-10-29 20:04:49 |
+-------+--------+----------+---------+-----------+---------------------+
1 row in set (0.01 sec)

数据库中的bookCount实际是2. 到底是什么问题？请教各位，谢谢