Question

在这样的查询中：

SELECT GROUP_CONCAT(DISTINCT( p.products_id )) AS comma_separated 
FROM   products p 
       left join specials s 
              ON p.products_id = s.products_id 
       left join products_to_categories p2c 
              ON p.products_id = p2c.products_id 
       left join products_description pd 
              ON p.products_id = pd.products_id 
       inner join products_attributes pa 
               ON p.products_id = pa.products_id 
WHERE  p.products_status = '1' 
       AND p2c.categories_id = 57 
       AND Date_sub(Curdate(), interval 7000 day) <= p.products_date_added 
ORDER  BY p.products_id DESC

我在名为comma_separated的字段中获得了逗号分隔数字的长列表结果。如何修改查询以计算有多少逗号分隔值？

修改

谢谢，Barmar的答案如下。我继续得到一个更短的数字列表（107个值而不是实际计数中的4000+），现在我终于找到了原因。似乎GROUP_CONCAT限制为1024个字符，这对我的应用程序来说非常糟糕。资料来源：http://www.bennadel.com/blog/2669-mysql-group-concat-fails-silently-when-it-hits-its-size-limit.htm

Answer 1

使用COUNT来计算它们。

SELECT Group_concat(DISTINCT( p.products_id )) AS comma_separated,
       COUNT(DISTINCT p.products_id) AS product_count
FROM ...

如何计算GROUP_CONCAT中有多少逗号分隔值

1 个答案: