php - mysql 查询不断返回重复的结果

Question

我有一个返回重复结果的查询。这是:

$product_sql_test2 = $this->db->query("SELECT p.product_id, p.price,    pc.product_id AS product_id
FROM oc_product p
INNER JOIN oc_product_to_category pc ON p.product_id = pc.product_id
WHERE p.price  BETWEEN '".$product_info['related_kv4nt_min_2']."' and '".$product_info['related_kv4nt_max_2']."'
AND pc.category_id =  '".$product_info['related_kv4nt_id_2']."'
GROUP BY pc.product_id
ORDER BY RAND( ) 
LIMIT 0 , 10");

我尝试使用 array_unique 函数，但它没有做任何事情。可以做什么？

P.s.我以前问过类似的问题，但没有得到答案，链接是: previous question with full source code.

致以诚挚的问候博格丹

p.p.s。现在源代码

if(isset($product_info['related_kv4nt_id_2'])) 
{
    $i=1;
    $imax = 5;
    while ($i < $imax) 
    {
        $product_sql_test2 = $this->db->query("SELECT DISTINCT p.product_id, p.price,    pc.product_id AS product_id
                                                FROM oc_product p
                                                INNER JOIN oc_product_to_category pc ON p.product_id = pc.product_id
                                                WHERE p.price  BETWEEN '".$product_info['related_kv4nt_min_2']."' and '".$product_info['related_kv4nt_max_2']."'
                                                AND pc.category_id =  '".$product_info['related_kv4nt_id_2']."'
                                                GROUP BY pc.product_id
                                                ORDER BY RAND( ) 
                                                LIMIT 0 , 10");
        if(isset($product_sql_test2->row['product_id']))
        {
            $this->data['product_spec_2_'.$i.''] = $product_sql_test2->row['product_id'];
        }
        $i++;
    }
} 

Answer 1

尝试在 select 语句中添加 DISTINCT 子句 http://dev.mysql.com/doc/refman/5.0/en/distinct-optimization.html