带有 GROUP_CONCAT 和 CONCAT 的子查询返回仍然超过 1 行，错误 1242

Question

我得到这个错误：

"错误1242多于1行"；

即使我已经准备好使用group_concat。。

这是我的查询，它给了我错误的

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"；硬编码"；id为的coms_exam_event_id只有1行，因此它正在工作-不知道为什么GROUP_CONCT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`

谢谢你的帮助抢劫

Answer 1

在group_concat中似乎不允许计数。我创建了一个HELP VIEW；选择concat。。。计数部分"；然后从视图中执行group_concat。。。