表 __hikashop_category
category_id category_name
表 __hikashop_product_category
id category_id product_id
表 __hikashop_product
id product_id product_name
已知表 __hikashop_category 中的category_id = 13 获得 hikashop_product 中 的 product_name
SELECT c.product_name FROM
`#__hikashop_category` as a,
`#__hikashop_product_category` as b,
`#__hikashop_product` as c
WHERE
b.category_id = a.category_id AND
c.product_id = b.product_id AND
a.category_id = 13;
** 对查询结果 进行 分组操作
GROUP BY
** 同样的操作使用 INNER JOIN
$query = 'SELECT c.product_id,c.product_name,c.product_msrp,d.file_path,e.price_value FROM `#__hikashop_category` as a '; $query .= 'INNER JOIN `#__hikashop_product_category` as b ON b.category_id = a.category_id '; $query .= 'INNER JOIN `#__hikashop_product` as c ON c.product_id = b.product_id '; $query .= 'INNER JOIN `#__hikashop_file` as d ON d.file_ref_id = c.product_id '; $query .= 'INNER JOIN `#__hikashop_price` as e ON e.price_product_id = d.file_ref_id '; $query .= 'WHERE a.category_id = 1'; $query .= ' GROUP BY c.product_id ORDER BY c.product_id DESC';