来自不同表的sql多计数

Question

如何获得推荐人的所有线索和点击？

表格：hits_log

+-----------+----------+
| topic     | referer  |
+-----------+----------+
| topic0614 | xxxxxxxx |
| topic0614 | xxxxxxxx |
| topic0615 | zzzzz    |
| topic0615 | yyyyyy   |
| topic0614 | xxxxxxxx |
| topic0614 | xxxxxxxx |
| topic0615 | zzzzz    |
| topic0615 | yyyyyy   |
| topic0614 | yyyyyy   |
| topic0614 | yyyyyy   |
| topic0615 | zzzzz    |
| topic0615 | yyyyyy   |
+-----------+----------+

表：Leads_log

+-----------+----------+
| topic     | referer  |
+-----------+----------+
| topic0614 | xxxxxxxx |
| topic0614 | xxxxxxxx |
| topic0614 | xxxxxxxx |
| topic0615 | zzzzz    |
| topic0615 | yyyyyy   |
| topic0614 | xxxxxxxx |
| topic0615 | zzzzz    |
| topic0614 | yyyyyy   |
+-----------+----------+

我想要这样的结果如果搜索主题为topic0614

+-----------+----------+------------+
| referer   | hits     | leads      |
+-----------+----------+------------+
| xxxxxxxx  | 4        | 4          |
| yyyyyy    | 2        | 1          |
+-----------+----------+------------+

我努力了

SELECT h.referer, COUNT(h.referer)  as hits, COUNT(l.referer)  as leads FROM `hits_log` h ,`leads_log` l
WHERE h.topic='topic0614' and h.referer=l.referer
GROUP BY h.referer 

但这没用

谁能帮我吗？ 谢谢。

Answer 1

您需要在子查询中将每个表分别分组。 如果您在主查询中进行计数，那么您正在计算叉积的结果，这会导致乘法。

SELECT h.referer, hits, leads
FROM (SELECT referer, COUNT(*) AS hits
      FROM hits_log
      WHERE topic = 'topic0614'
      GROUP BY referer) AS h
JOIN (SELECT referer, COUNT(*) AS leads
      FROM leads_log
      GROUP BY referer) AS l
ON h.referer = l.referer

DEMO

也许这实际上是您想要的。 它既限制了匹配，又限制了针对特定主题的访问，并且在两个表中都将包括零计数的引用。

SELECT referer, MAX(hits) AS hits, MAX(leads) AS leads
FROM (SELECT referer, COUNT(*) AS hits, 0 as leads
      FROM hits_log
      WHERE topic = 'topic0614'
      GROUP BY referer
      UNION
      SELECT referer, 0 AS hits, COUNT(*) as leads
      FROM leads_log
      WHERE topic = 'topic0614'
      GROUP BY referer) AS x
GROUP BY referer

DEMO