通过连接库存和要素表，使用数组到字符串显示库存的特征

'stock' table >>
        stock_id    integer     NOT NULL AUTO_INCREMENT,
        modal       varchar(40) NOT NULL DEFAULT "",
        company     varchar(40) NOT NULL DEFAULT "",
        bike_number varchar(10) NOT NULL DEFAULT "",
        lair_id     integer     NOT NULL DEFAULT 0,
        PRIMARY KEY(stock_id)   

'feature' table >>
        feature_id  integer     NOT NULL    AUTO_INCREMENT,
        feature     varchar(40) NOT NULL    DEFAULT "",
        primary key (feature_id)

'stock_feature' linking table >>
        stock_id    integer     NOT NULL,
        feature_id  integer     NOT NULL,
        primary key(stock_id, feature_id)   

I retrieved the stock_id using query1 and have it as $row['stock_id']. I want to display all the feature for this stock_id by saving the feature in array first.

Here is my code which is not working

$query2='SELECT feature FROM feature f JOIN stock_feature sf ON f.feature_id=sf.feature_id WHERE sf.stock_id='.$row['stock_id'];
            $result2=mysqli_query($db, $query2) or die(mysqli_error($db));

        if(mysqli_num_rows($result2)>0){
            $features=array();
            while($row2=mysqli_fetch_assoc($result2)){
                $features[]=$row2['feature'];
            }
        echo '<td>' . implode (', ', $features) . '</td>';
        }else{
             echo '<td> No significant feature </td>';
              }