[英]Can a mysql query return all of an entities fields in single row?
我正在嘗試為建築物及其所有信息設置架構。
因為建築物的區域數量可以變化,所以我將這些區域存儲在表“ areas”中,其中每個區域都有一個外鍵指向其所屬建築物的主鍵。
我想要的是嘗試在一條線上獲得建築物的所有信息,例如:
--------------------------------------------------------------------
id | address | owner | area 1 | area 2 | area 3 |
--------------------------------------------------------------------
1 | 21 kingsbridge st | claudia | kitchen | bathroom | garage|
--------------------------------------------------------------------
使用LEFT JOIN
我可以獲得信息,只是格式不是Im之后
我在這里http://www.sqlfiddle.com/#!9/83558/6設置了架構
希望有一個類似GROUP BY之類的聚合函數之類的查詢? 這可能嗎?
select x.pId, x.address, x.owner,
max(x.area1) A1, max(x.area2) A2,max(x.area3) A3,max(x.area4) A4,max(x.area5) A5
from
(
SELECT p.id pId, p.address, p.owner, a.id aId, a.property_id, a.area_name,
case when a.area_name = 'kitchen' then a.area_name else null end as area1,
case when a.area_name = 'garage' then a.area_name else null end as area2,
case when a.area_name = 'checkout' then a.area_name else null end as area3,
case when a.area_name = 'booths' then a.area_name else null end as area4,
case when a.area_name = 'bathroom' then a.area_name else null end as area5
FROM properties p
LEFT JOIN areas a
ON p.id = a.property_id
) as X
GROUP BY pId, x.address, x.owner
但是您需要知道哪些是不同的領域。
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