我知道这可能无法回答,但我想弄清楚为什么查询返回0结果。
SELECT SQL_CALC_FOUND_ROWS
records.instance_id
,instances.patient_id
,form_1_data.field_1 AS field_0
,form_1_data.field_2 AS field_1
,records.field_240 AS field_2
,**GROUP_CONCAT(events.start_time SEPARATOR '<br />')** AS field_3
FROM form_4_data AS records
LEFT JOIN instances ON instances.id= records.instance_id
LEFT JOIN events ON records.instance_id = events.instance_id
LEFT JOIN form_3_data ON records.field_111= form_3_data.instance_id
LEFT JOIN form_1_data ON form_3_data.field_94= form_1_data.instance_id
WHERE instances.active=1
ORDER BY records.instance_id DESC
LIMIT 25,25
返回0结果。
但是,
SELECT SQL_CALC_FOUND_ROWS
records.instance_id
,instances.patient_id
,form_1_data.field_1 AS field_0
,form_1_data.field_2 AS field_1
,records.field_240 AS field_2
,**events.start_time AS field_3**
FROM form_4_data AS records
LEFT JOIN instances ON instances.id= records.instance_id
LEFT JOIN events ON records.instance_id = events.instance_id
LEFT JOIN form_3_data ON records.field_111= form_3_data.instance_id
LEFT JOIN form_1_data ON form_3_data.field_94= form_1_data.instance_id
WHERE instances.active = 1
ORDER BY records.instance_id DESC
LIMIT 25,25
返回:
instance_id patient_id field_0 field_1 field_2 field_3
83 40 Jack Nichols NULL 2011-04-11 20:00:00
60 8 Olive Miller Split NULL
58 32 Mark Green NPSG 2011-03-05 20:00:00
58 32 Mark Green NPSG 2011-04-09 20:00:00
58 32 Mark Green NPSG 2011-04-02 20:00:00
58 32 Mark Green NPSG 2011-04-09 20:00:00
57 32 Mark Green MSLT NULL
56 43 Jeremy Stevens NPSG NULL
31 32 Mark Green MWT 2011-04-14 20:00:00
28 29 Jerry Jones NULL 2011-04-01 20:00:00
28 29 Jerry Jones NULL 2011-04-02 20:00:00
28 29 Jerry Jones NULL 2011-03-30 20:00:00
28 29 Jerry Jones NULL 2011-04-01 20:00:00
28 29 Jerry Jones NULL 2011-04-14 20:00:00
11 8 Olive Miller Split 2011-03-11 20:00:00
11 8 Olive Miller Split 2011-03-30 20:00:00
11 8 Olive Miller Split 2011-03-22 20:00:00
11 8 Olive Miller Split 2011-04-06 20:00:00
11 8 Olive Miller Split 2011-04-16 20:00:00
11 8 Olive Miller Split 2011-03-31 20:00:00
11 8 Olive Miller Split 2011-04-02 20:00:00
11 8 Olive Miller Split 2011-04-03 20:00:00
9 8 Olive Miller NPSG 2011-04-22 20:00:00
9 8 Olive Miller NPSG 2011-03-29 20:00:00
9 8 Olive Miller NPSG 2011-03-29 20:00:00
答案 0 :(得分:1)
group_concat
不起作用,因为您的查询中没有group by
子句
添加group by
即可。
SELECT SQL_CALC_FOUND_ROWS
records.instance_id
,instances.patient_id
,form_1_data.field_1 AS field_0
,form_1_data.field_2 AS field_1
,records.field_240 AS field_2
GROUP_CONCAT(events.start_time SEPARATOR '<br />') AS field_3
FROM form_4_data AS records
LEFT JOIN instances ON instances.id= records.instance_id
LEFT JOIN events ON records.instance_id = events.instance_id
LEFT JOIN form_3_data ON records.field_111= form_3_data.instance_id
LEFT JOIN form_1_data ON form_3_data.field_94= form_1_data.instance_id
WHERE instances.active=1
GROUP BY records.instance_id /*<<-- addition */
ORDER BY records.instance_id DESC
LIMIT 25,25
答案 1 :(得分:0)
如果您只想在日期中添加新行,则GROUP_CONCAT不是您真正需要的。它是一个与GROUP BY一起使用的聚合函数,用于连接分组块中不同行的字符串。
如果我们有一个表周:
week weekday
1 Monday
1 Tuesday
1 Friday
2 Monday
2 Sunday
查询
SELECT week, GROUP_CONCAT( weekday SEPARATOR '<br />' ) as days
FROM weeks
GROUP BY week
会给你:
week days
1 Monday<br />Tuesday<br />Friday
2 Monday<br />Sunday
我相信你要找的是一个简单的CONCAT:
SELECT week, CONCAT( weekday,'<br />' ) as day
FROM weeks
会给你:
week day
1 Monday<br />
1 Tuesday<br />
1 Friday<br />
2 Monday<br />
2 Sunday<br />