Question

短

我想基于SUM TABLE_A CRITERIA X列TABLE_B.total_x并插入SUM
我想基于TABLE_A CRITERIA Y TABLE_B.total_y列TABLE_B.total_y并插入| year | month | type | total | --------------------------------------- | 2013 | 11 | down | 100 | | 2013 | 11 | down | 50 | | 2013 | 11 | up | 60 | | 2013 | 10 | down | 200 | | 2013 | 10 | up | 15 | | 2013 | 10 | up | 9 |
问题：第2步未更新CREATE TABLE `TABLE_B` ( `year` INT(4) NULL DEFAULT NULL, `month` INT(2) UNSIGNED ZEROFILL NULL DEFAULT NULL, `total_x` INT(10) NULL DEFAULT NULL, `total_y` INT(10) NULL DEFAULT NULL, UNIQUE INDEX `unique` (`year`, `month`) )

LONG

TABLE_A：数据

INSERT INTO TABLE_B (
 `year`, `month`, `total_x`
)
SELECT 
  t.`year`, t.`month`,
  SUM(t.`total`) as total_x
FROM TABLE_A t
WHERE
  t.`type` = 'down'
GROUP BY
  t.`year`, t.`month`
 ON DUPLICATE KEY UPDATE
  `total_x` = total_x
;

TABLE_B：结构

INSERT INTO TABLE_B (
 `year`, `month`, `total_y`
)
SELECT 
  t.`year`, t.`month`,
  SUM(t.`total`) as total_y
FROM TABLE_A t
WHERE
  t.`type` = 'up'
GROUP BY
  t.`year`, t.`month`
 ON DUPLICATE KEY UPDATE
  `total_y` = total_y
;

SQL：CRITERIA_X

total_y

SQL：CRITERIA_Y

{{1}}

第二个SQL（CRITERIA_Y）未按预期更新{{1}}。的 WHY吗

Answer 1

我会采取另一种方式

insert into TABLE_B (year, month, total_x, total_y)
select year, month
     , sum (case [type] when 'down' then [total] else 0 end) [total_x]
     , sum (case [type] when 'up' then [total] else 0 end) [total_y]
from TABLE_A
group by [year], [month]

或者使用两个子查询的方式是

insert into TABLE_B (year, month, total_x, total_y)
select coalesce(t1.year, t2.year) year
     , coalesce(t1.month, t2.month) month
     , t1.total_x total_x
     , t2.total_y total_y
from (select year, month, sum(total) total_x
         from TABLE_A where [type]='down') t1 
full outer join
     (select year, month, sum(total) total_y
         from TABLE_A where [type]='up') t2
     on t1.year = t2.year and t1.month = t2.month

或使用union

insert into TABLE_B (year, month, total_x, total_y)
select year, month, sum(total_x), sum(total_y)
from ( 
   select year, month, sum(total) total_x, 0 total_y
   from TABLE_A where [type]='down'
   group by year, month
   union
   select year, month, 0 total_x, sum(total) total_y
   from TABLE_A where [type]='up'
   group by year, month) t
group by year, month

阅读关于INSERT的规范......在重复键更新时，我注意到了这一点：

如果...匹配多行，则只更新一行。通常，您应该尽量避免在具有多个唯一索引的表上使用ON DUPLICATE KEY UPDATE子句。

因此使用复合键的语法有点麻烦，我个人会避免使用它。

INSERT SELECT ON DUPLICATE不更新

1 个答案: