[英]MySQL query aggregate MAX and subquery
有没有一种方法可以从子查询中的select内部位置获取价值?
stop_link表
id | duid | domain_id
1 | 1 | 1
2 | 2 | 1
3 | 1 | 2
4 | 2 | 2
5 | 3 | 1
我想要的结果(假设domain_id = 2)
duid | domain_id
3 | 2
查询(不起作用):
INSERT INTO stop_link (
duid,
domain_id)
SELECT
IFNULL(MAX(sl.duid), 0) + 1 AS duid,
sl.domain_id
FROM
stop_link sl
WHERE sl.domain_id = (SELECT sd.id FROM stop_domain sd LIMIT 1)
查询工作,但我希望避免使用Set Variable:
SET @domain_id = (SELECT sd.id FROM stop_domain sd LIMIT 1);
SELECT
IFNULL(MAX(sl.duid), 0) + 1 AS duid
, @domain_id
FROM
stop_link sl
WHERE sl.domain_id = @domain_id;
您的意思是这样的吗:
/*Your example Table*/
DECLARE @T
TABLE(ID INT,duid INT,domain_id INT)
INSERT INTO @T
VALUES
(1 , 1 , 1 ),
(2 , 2 , 1),
(3 , 1 , 2),
(4 , 2 , 2),
(5 , 3 , 1)
--The query
SELECT domain_id,Isnull(max(duid),0)+1 [newId]
FROM @T
GROUP BY domain_id
根据评论中的新信息更改了答案。 听起来您在only_full_group_by
启用了sql_mode
。 您的查询可能会与该残疾人士一起使用,但以下内容也可能对您有用:
INSERT INTO stop_link (
duid,
domain_id)
SELECT
IFNULL(MAX(sl.duid), 0) + 1 AS duid,
sl.domain_id
FROM
stop_link sl
WHERE sl.domain_id = (SELECT sd.id FROM stop_domain sd LIMIT 1)
-- ORDER by sl.domain_id DESC LIMIT 1 # Removed in favor of the following line
GROUP BY sl.domain_id HAVING MAX(sl.id)
;
请注意,子查询可能没有返回您想要的stop_domain.id
您可能打算选择MAX(sd.id),或者为了清楚起见,您只是删除了WHERE sd.url='foo'
。
不需要max()
:
SELECT
IFNULL(sl.duid, 0) + 1 AS duid,
sl.domain_id
FROM
stop_link sl
WHERE sl.domain_id = (SELECT sd.id FROM stop_domain sd LIMIT 1)
ORDER by sl.id DESC
LIMIT 1
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