Question

我正在寻找解决方案：

SELECT SUM(`quant`), MONTH(`date`) AS month, `id` from (
(SELECT `date`, `id`, count(`hit`) AS `quant ` FROM `stat_2014_07` WHERE `k_id` = '123') 
UNION ALL 
(SELECT `date`, `id`, count(`hit`) AS `quant ` FROM `stat_2014_08` WHERE `k_id ` = '123') 
) group by id, month

MySQL：每个派生表都必须有自己的别名

Answer 1

错误消息的确切含义。在您的（简化）查询中：

SELECT SUM(`quant`), MONTH(`date`) AS month, `id` 
from (
  ... inner select 
) 
group by id, month;

您没有为派生表指定别名。所以它应该是：

SELECT SUM(`quant`), MONTH(`date`) AS month, `id` 
from (
  ... inner select 
) as t -- this is the change
group by id, month;

顺便说一句：联盟选择部分周围的括号完全没用。为清晰起见，我建议删除它们：

SELECT SUM(`quant`), MONTH(`date`) AS month, `id` 
from (
  SELECT `date`, `id`, count(`hit`) AS `quant ` FROM `stat_2014_07` WHERE `k_id` = '123'
  UNION ALL 
  SELECT `date`, `id`, count(`hit`) AS `quant ` FROM `stat_2014_08` WHERE `k_id ` = '123'
) as t -- this is the change
group by id, month;

Answer 2

您需要为查询提供别名：

SELECT   SUM(`quant`), MONTH(`date`) AS month, `id` 
FROM     ((SELECT `date`, `id`, count(`hit`) AS `quant` 
           FROM   `stat_2014_07` 
           WHERE  `k_id` = '123') t1
          UNION ALL 
          (SELECT `date`, `id`, count(`hit`) AS `quant` 
           FROM   `stat_2014_08` 
           WHERE  `k_id ` = '123') t2
         ) t_union
GROUP BY id, month

MySQL UNION - 每个派生表都必须有自己的别名

2 个答案: