Question

我正在尝试以下列格式生成表格。

Proday | 2014-04-01 | 2014-03-01
--------------------------------
  1    |      12    |     17
  2    |       6    |      0
  7    |       0    |     24
 13    |       3    |      7

Prodays（两个时间戳之间的持续时间）是计算值，月份数据是COUNT。我可以输出一个月的数据，但是在将查询加入其他月份时遇到了麻烦。每个月的指数（prodays）可能不匹配。例如，2014-04-01可能没有Prodays 7的任何数据，而2014-03-01可能没有Proday 2.应该表示0或null。

我怀疑FULL OUTER JOIN是应该做的诀窍。但是已经读过Mysql中不可能的内容吗？

这是获取单个月数据的查询：

SELECT round((protime - createtime) / 86400) AS prodays, COUNT(id) AS '2014-04-01'
FROM  `tbl_users` as t1
WHERE status = 1 AND DATE_FORMAT(FROM_UNIXTIME(createtime),'%Y-%m-%d') >= '2014-04-01'
AND DATE_FORMAT(FROM_UNIXTIME(createtime),'%Y-%m-%d') <= LAST_DAY('2014-04-01')
GROUP BY prodays
ORDER BY `prodays` ASC

如何加入/联合其他查询以创建2014-03-01的列？

Answer 1

您希望使用条件聚合 - 即将过滤逻辑从where子句移到select子句：

SELECT round((protime - createtime) / 86400) AS prodays,
       sum(DATE_FORMAT(FROM_UNIXTIME(createtime),'%Y-%m-%d') >= '2014-04-01' AND 
           DATE_FORMAT(FROM_UNIXTIME(createtime),'%Y-%m-%d') <= LAST_DAY('2014-04-01')
          ) as `2014-04-01`,
       sum(DATE_FORMAT(FROM_UNIXTIME(createtime),'%Y-%m-%d') >= '2014-03-01' AND 
           DATE_FORMAT(FROM_UNIXTIME(createtime),'%Y-%m-%d') <= LAST_DAY('2014-03-01')
          ) as `2014-03-01`
FROM  `tbl_users` as t1
WHERE status = 1
GROUP BY prodays
ORDER BY `prodays` ASC;

MySQL - 使用COUNT在同一个表上进行全外连接

1 个答案: