使用 union 连接两个查询只返回单个值？

Question

我合并了两个查询，其中 returning 3 列（月、计数、目标）通过分别执行这两个查询，它 return 给我 2 条正确的记录。但是 UNION ALL 它的 return 我只有一个值：

我的查询：

select s.month,COALESCE(max(s.count), NULL, 0) as count, COALESCE(max(s.targets), NULL, 0) as target from 
(SELECT MONTHNAME(tm.meeting_date) as month, count(DISTINCT tm.meeting_id) as count, NULL as targets 
FROM tig as t 
left join tig_meeting as tm ON t.tig_code = tm.tig_code 
WHERE tm.meeting_date IS NOT NULL AND tm.meeting_date != 0 AND t.school_district = 'Islamabad C3' 
AND (tm.meeting_date BETWEEN "2018-07-01" AND "2018-09-30") AND tm.key_support <> 'QuarterlyTigMeetings' AND tm.key_support <> 'QTIG_by_SSA' 
AND tm.key_support <> 'MTIG_by_SSA' AND tm.meeting_no NOT LIKE '%RF' 
GROUP BY MONTH(tm.meeting_date) 
UNION ALL 
SELECT mpt.month, NULL as count, SUM(mpt.monthly_target) as targets 
FROM meeting_plan_targets mpt 
LEFT JOIN meeting_plans mp ON mp.id = mpt.meeting_plan_id 
WHERE mp.district = 'Islamabad C3' AND mp.module_title = 1 AND mp.year = 2018 AND mp.quarter = "Quarter 4" GROUP BY mpt.month) s 
group by MONTH(s.month)

供参考，请查看附图

Answer 1

你可以试试下面

select s.`month`,COALESCE(max(s.count),0) as count, COALESCE(max(s.targets),0) as target from 
(
SELECT MONTHNAME(tm.meeting_date) as `month`,MONTH(tm.meeting_date) as monnum,count(DISTINCT tm.meeting_id) as count, NULL as targets 
FROM tig as t 
left join tig_meeting as tm ON t.tig_code = tm.tig_code 
WHERE tm.meeting_date IS NOT NULL AND tm.meeting_date != 0 AND t.school_district = 'Islamabad C3' 
AND (tm.meeting_date BETWEEN '2018-07-01' AND '2018-09-30') AND tm.key_support <> 'QuarterlyTigMeetings' AND tm.key_support <> 'QTIG_by_SSA' 
AND tm.key_support <> 'MTIG_by_SSA' AND tm.meeting_no NOT LIKE '%RF' 
GROUP BY MONTHNAME(tm.meeting_date),MONTH(tm.meeting_date)

UNION ALL 

SELECT MONTHNAME(mpt.month), MONTH(mpt.month),NULL as count, SUM(mpt.monthly_target) as targets 
FROM meeting_plan_targets mpt 
LEFT JOIN meeting_plans mp ON mp.id = mpt.meeting_plan_id 
WHERE mp.district = 'Islamabad C3' AND mp.module_title = 1 AND mp.year = 2018 AND mp.quarter = 'Quarter 4' 
GROUP BY MONTHNAME(mpt.month),MONTH(mpt.month)
) s 
group by s.`month`,monnum order by monnum

Answer 2

s.month 是月份名称。 MONTH(s.month) 不起作用，因为 MONTH() 函数期望其参数是日期或日期时间（或可以解析为日期或日期时间的字符串），而不是月份名称。

改用GROUP BY s.month。

使用 union 连接两个查询只返回单个值？

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