Question

这是我的表的一个例子。对于给定的post_id，我在多行上有多个条目（这是帖子的元数据）。

post_id | meta_key | meta_value
________ __________ ___________
        |          |
1       | _theDate | 2016-03-31 
1       | _email   | the@email.com
2       | _theDate | 2016-01-06 
2       | _email   | the@email.com
3       | _theDate | 2017-02-14 
3       | _email   | other@user.net
4       | _theDate | 2016-10-01 
4       | _email   | the@email.com
5       | _theDate | 2016-09-25 
5       | _email   | other@user.net
6       | _theDate | 2015-11-19 
6       | _email   | other@user.net

我想要完成的任务：

我想查找邮件地址the@email.com和年份＆＃34; 2016年＆＃34;在元数据中，然后计算这些单独的帖子，以查找用户the@email.com在一年中所写的帖子数量＆＃34; 2016＆＃34;。

目前我设法只使用

查找电子邮件地址的实例

SELECT DISTINCT post_id 
FROM  metatable 
WHERE meta_value LIKE '%the@email.com%'

这会计算该用户的总帖子数，但不仅计入2016年的帖子。

Answer 1

以下是一种使用两级聚合的方法：

SELECT COUNT(*)
FROM (SELECT post_id
      FROM  metatable 
      WHERE (meta_key = '_email' AND meta_value = 'the@email.com') OR
            (meta_key = '_theDate' AND LEFT(meta_value, 4) = '2016')
      GROUP BY post_id
      HAVING COUNT(DISTINCT meta_key) = 2
     ) p;

编辑：缺少报价

Answer 2

你走了：

SELECT t.post_id -- Replace with `SELECT count(*)` to just have the total
FROM table t
WHERE t.meta_key = '_email' AND t.meta_value = 'the@email.com' AND 
      EXISTS (
                SELECT 1
                FROM table
                WHERE post_id = t.post_id AND YEAR(meta_value) = 2016
                      meta_key = '_theDate' AND meta_value = xxx
             );

Answer 3

SELECT
    COUNT(*)
FROM
    metatable m1
    INNER JOIN metatable m2 ON m2.post_id = m1.post_id
WHERE
    AND m1.meta_key = _theDate
    AND m1.meta_value LIKE '2016%'
    AND m2.meta_key = _email
    AND m2.meta_value = 'the@email.com'

Answer 4

首先加入自己的表格，以便获得一个“用户 - 日期”＆＃39;结构化表格：

SELECT email.post_id, email.meta_value as mail, date.meta_value as date from metatable as email
 inner join metatable as dateTable
 on email.post_id = dateTable.post_id
 and email.meta_key = '_email'
 and dateTable.meta_key = '_theDate'

在那你可以做你想做的事：

SELECT count(*) from metatable as email
 inner join metatable as dateTable
 on email.post_id = dateTable.post_id
 and email.meta_key = '_email'
 and dateTable.meta_key = '_theDate'
 where
 email.meta_value = 'the@email.com'
 and date.meta_value like '2016%';

Answer 5

考虑到你想要计算meta_key的所有位置＆＃34; _theDate＆＃34;选择将：

SELECT COUNT(1) FROM table WHERE YEAR(aux_meta_value) = "2016" AND meta_key = '_theDate'

需要有关此SQL查询的帮助

5 个答案: