MySQL SELECT OpenCarts 数据库中的重复行

只是玩一下 OpenCart DB，看看我是否能学到一些东西。 如果我使用以下SELECT结果返回重复的行：

SELECT DISTINCT
p.product_id AS pid,
p.model AS modelo,
SUBSTRING(p.model,1,25) AS substr_modelo,
p.image AS foto,
p.price AS preco,
pd.name AS nome,
cd.name AS category
FROM product p
LEFT JOIN product_description pd ON p.product_id = pd.product_id
LEFT JOIN product_to_category p2c ON p.product_id = p2c.product_id
LEFT JOIN category_description cd ON p2c.category_id = cd.category_id
WHERE pd.name LIKE _utf8 'laser%' collate utf8_unicode_ci
ORDER BY p.product_id DESC

请注意，即使使用DISTINCT它是重复的，但是如果我添加一个按 p.product_id 分组它停止复制行。这是最好的解决方案吗？

DISTINCT删除重复的整行.

Use GROUP BY p.product_id每个产品 ID 显示 1 行。

注意：如果按product_id分组，如果您有多个产品描述、多个类别或多个类别描述，则查询将为每个返回随机行。使用MIN() http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_min or MAX() http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_max函数来检索单个 ID，或使用GROUP_CONCAT() http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat函数检索所有描述。

Example

SELECT
  p.product_id AS pid,
  p.model AS modelo,
  SUBSTRING(p.model,1,25) AS substr_modelo,
  p.image AS foto,
  p.price AS preco,
  GROUP_CONCAT(pd.name) AS nome,
  GROUP_CONCAT(cd.name) AS category
FROM product p
  LEFT JOIN product_description pd ON p.product_id = pd.product_id
  LEFT JOIN product_to_category p2c ON p.product_id = p2c.product_id
  LEFT JOIN category_description cd ON p2c.category_id = cd.category_id
  WHERE pd.name LIKE _utf8 'laser%' collate utf8_unicode_ci
GROUP BY p.product_id
ORDER BY p.product_id DESC