Question

我曾经有过查询

SELECT ps_target_ecpm, ps_actual_ecpm
FROM publisher_stats
JOIN domain ON domain.dmn_id = ps_dmn_id
LEFT JOIN langue ON langue.lng_id = domain.default_lng_id
WHERE MONTH(ps_month) = 05

我需要的结果应该是

may_target_ecmp，may_actual_ecpm，april_target_ecpm，   april_actual_ecpm，march_target_ecpm，march_actual_ecpm。

对于4月MONTH（ps_month）= 04和3月MONTH（ps_month）= 03   分别

经过一些询问，我最终得到了一个看起来像这样的查询

SELECT
(CASE WHEN MONTH(ps_month) = 4 THEN ps_target_ecpm ELSE 0 END) AS april_target_ecpm, 
(CASE WHEN MONTH(ps_month) = 4 THEN ps_actual_ecpm ELSE 0 END) AS april_actual_ecpm,
(CASE WHEN MONTH(ps_month) = 3 THEN ps_target_ecpm ELSE 0 END) AS march_target_ecpm, 
(CASE WHEN MONTH(ps_month) = 3 THEN ps_actual_ecpm ELSE 0 END) AS march_actual_ecpm 
FROM publisher_stats
JOIN domain ON domain.dmn_id = ps_dmn_id
LEFT JOIN langue ON langue.lng_id = domain.default_lng_id

我得到的结果集并不是我需要的。示例响应是：

0           0       0.48    0.27
0.48        0.47    0       0

虽然我需要它在一行

0.48    0.47    0.48    0.27

您能否帮我弄清楚如何使此查询按预期执行。提前致谢

P.S。这个问题从这个问题开始 - mysql pivoting - how can I fetch data from the same table into different columns?

Answer 1

只需使用聚合函数，MAX例如可以正常工作，但如果需要获取每月的总数，则可能需要使用SUM，如果{ps_target_ecpm有多个条目1}}每个月。像这样：

SELECT
  MAX(CASE WHEN MONTH(ps_month) = 4 THEN ps_target_ecpm ELSE 0 END) AS april_target_ecpm, 
  MAX(CASE WHEN MONTH(ps_month) = 4 THEN ps_actual_ecpm ELSE 0 END) AS april_actual_ecpm,
  MAX(CASE WHEN MONTH(ps_month) = 3 THEN ps_target_ecpm ELSE 0 END) AS march_target_ecpm, 
  MAX(CASE WHEN MONTH(ps_month) = 3 THEN ps_actual_ecpm ELSE 0 END) AS march_actual_ecpm 
FROM publisher_stats
JOIN domain ON domain.dmn_id = ps_dmn_id
LEFT JOIN langue ON langue.lng_id = domain.default_lng_id

MySQL数据透视查询

1 个答案: