MySQL count 来自多个表的列。按主 ID 分组结果答案

【问题标题】：MySQL count column from multiple tables. Group results by primary idMySQL count 来自多个表的列。按主 ID 分组结果
【发布时间】：2015-10-12 09:25:56
【问题描述】：

我有以下 3 个 MySQL 表：

products

|编号 |姓名 |评论数 | |----|------------|---------------| | 1 |产品A | 10 | | 2 |产品B | 20 | | 3 |产品C | 30 |

products_views

|产品编号 | pv_count | pv_date | | -----------|-------|------------| | 1 | 10 | 2015-01-01 | | 1 | 10 | 2015-01-02 | | 1 | 10 | 2015-01-03 | | 2 | 20 | 2015-01-01 | | 2 | 20 | 2015-01-02 | | 2 | 20 | 2015-01-03 | | 3 | 30 | 2015-01-01 | | 3 | 30 | 2015-01-02 | | 3 | 30 | 2015-01-03 |

products_likes

|产品编号 | pl_count | pl_date | | -----------|-------|------------| | 1 | 10 | 2015-01-01 | | 1 | 10 | 2015-01-02 | | 1 | 10 | 2015-01-03 | | 2 | 20 | 2015-01-01 | | 2 | 20 | 2015-01-02 | | 2 | 20 | 2015-01-03 | | 3 | 30 | 2015-01-01 | | 3 | 30 | 2015-01-02 | | 3 | 30 | 2015-01-03 |

我想将products.comment_count + product_views.count + product_likes.count 按products.id 分组在一起，其中product_views.pv_date 和product_likes.pl_date 在2015-01-01 和2015-01-03 之间。通过total 订购。

我想要的是： |产品编号 |总计| | ------------|--------| | 3 | 210 | | 2 | 140 | | 1 | 70 |

【问题讨论】：

标签： php mysql count sum

【解决方案1】：

试试这个查询

SELECT 
   p.product_id, 
  (p.comment_count + SUM(pv.count) + SUM(pl.count)) AS total
 FROM products p
 JOIN products_views pv ON( p.product_id = pv.product_id)
 JOIN products_likes pl ON( p.product_id = pl.product_id)
 WHERE pl.date BETWEEN '2015-01-01' AND '2015-01-03'
  AND pv.date BETWEEN '2015-01-01' AND '2015-01-03'
 GROUP BY p.product_id   
 ORDER BY total DESC

【讨论】：

【解决方案2】：

SELECT 
    (products.comment_count+products_views.pv_count+products_likes.pl_count) AS    product_count
    FROM products 
    INNER JOIN products_views.product_id=products.id
    INNER JOIN products_likes.product_id=products.id
    WHERE  (product_views.pv_date BETWEEN dateVal AND dateVal) 
    AND (products_likes.pl_date BETWEEN dateVal AND dateVal) 
   GROUP BY     products.id
   ORDER BY  product_count

【讨论】：

【解决方案3】：

在加入之前执行“每个表”的计数，否则您可能会获得比应有的结果更大的结果，因为联接可以使行数成倍增加。此外，由于喜欢或视图中可能不存在某些产品，因此建议对两个“派生表”进行左外连接。

SELECT
      p.product_id
    , (IFNULL(p.comment_count,0) + IFNULL(pv.view_count, 0) + IFNULL(pl.like_count, 0)) AS total
FROM products p
      LEFT OUTER JOIN (
            SELECT
                  product_id
                , SUM(`count`) AS view_count
            FROM products_views
            WHERE `date` BETWEEN '2015-01-01' AND '2015-01-03'
            GROUP BY
                  product_id
      ) pv ON p.product_id = pv.product_id
      LEFT OUTER JOIN (
            SELECT
                  product_id
                , SUM(`count`) AS like_count
            FROM products_likes
            WHERE `date` BETWEEN '2015-01-01' AND '2015-01-03'
            GROUP BY
                  product_id
      ) pl ON p.product_id = pl.product_id
GROUP BY
      p.product_id
ORDER BY
      total DESC

顺便说一句：date 和count 是大多数 SQL 方言中的保留字；将列命名为date 或count 不是一个好主意；使用更多的东西，例如date_entered、date_created、view_count、like_count 等。

【讨论】：

【解决方案4】：

select p.product_id, sum(p.comment_count) + sum(v.count) + sum(l.count) as total from products p join products_views v on p.product_id = v.product_id join products_likes l on p.product_id = l.product_id group by p.product_id
where l.date between '2015-01-01' and '2015-01-03'
order by total desc

试试这个

【讨论】：

查询结构错误... GROUP BY 应该在 WHERE 之后