带有 GROUP_CONCAT 和 CONCAT 的子查询返回 STILL 多于 1 行，错误 1242

Posted 2023-02-24

【中文标题】带有 GROUP_CONCAT 和 CONCAT 的子查询返回 STILL 多于 1 行，错误 1242

【英文标题】：Subquery with GROUP_CONCAT & CONCAT returns STILL more than 1 row, Error 1242

【发布时间】：2021-07-14 16:55:19

【问题描述】：

我得到这个错误：

“错误 1242 超过 1 行”

即使我已经使用 group_concat ..

这是我的查询，它给了我错误

SELECT 
`coms_participant_exam_event`.`coms_exam_event_id` AS PEE_ID,
(SELECT GROUP_CONCAT((SELECT CONCAT(`bpmspace_coms_v1`.`state`.`name`," (",`coms_participant_exam_event`.`state_id`,") ",  count(`coms_participant_exam_event`.`state_id`))  
FROM `coms_participant_exam_event`
JOIN `bpmspace_coms_v1`.`state` ON
    (
            `bpmspace_coms_v1`.`state`.`state_id` =
            `bpmspace_coms_v1`.`coms_participant_exam_event`.`state_id`
    )
where `coms_exam_event_id` = `coms_participant_exam_event`.`coms_exam_event_id`
group by `bpmspace_coms_v1`.`coms_participant_exam_event`.`state_id`) , ','))
FROM `coms_participant_exam_event`
group by `coms_participant_exam_event`.`coms_exam_event_id`

当我用一个 id “硬编码”coms_exam_event_id 时，它只有 1 行，因为它正在工作 - 不知道为什么 GROUP_CONCAT 不够

SELECT 
`coms_participant_exam_event`.`coms_exam_event_id` AS PEE_ID,
(SELECT GROUP_CONCAT((SELECT CONCAT(`bpmspace_coms_v1`.`state`.`name`," (",`coms_participant_exam_event`.`state_id`,") ",  count(`coms_participant_exam_event`.`state_id`))  
FROM `coms_participant_exam_event`
JOIN `bpmspace_coms_v1`.`state` ON
    (
            `bpmspace_coms_v1`.`state`.`state_id` =
            `bpmspace_coms_v1`.`coms_participant_exam_event`.`state_id`
    )
where `coms_exam_event_id` = 877523
group by `bpmspace_coms_v1`.`coms_participant_exam_event`.`state_id`),','))
FROM `coms_participant_exam_event`
group by `coms_participant_exam_event`.`coms_exam_event_id`

感谢您的帮助 抢

【参考方案1】：

在 group_concat 中似乎不允许计数。 我用“select concat ... count ... part”创建了一个 HELP VIEW，然后从视图中做了 group_concat ...