我知道这可能无法回答,但我正在尝试找出查询返回 0 个结果的原因。
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 个结果。
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
最佳答案
group_concat
不起作用,因为您的查询中没有 group by
子句。
添加一个 group by
就可以了。
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
关于mysql - 组连接查询问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5796562/