從多個表中選擇多個列

示例。
我有兩個表從多個表中選擇多個列

CAR 
id name 
1 bmw 
2 fiat 

Car_info 
car_id field_name country 
    1  year   2000 
    1  country  germany 
    2  year   1988 
    2  country  italy

如何在一個選擇查詢我能得到這個？

id name year country 
1 bmw 2000 germany 
2 fiat 1988 italy

來源

2013-03-21 cosset

爲什麼您的Car_info上的「國家/地區」列包含年份和國家/地區？不應該把這個列命名爲'field_val'，因爲它的名字被設置爲'field_name'？ – fcm 2013-03-21 11:12:02

理想情況下，您應該在car_info表中指定一列，指定在該行上顯示的信息類型。即類型1是年份，類型2是國家。

你可以避開這個問題通過加入到car_info表上加入兩次指定「與」條件，就像這樣：

SELECT car.ID, car.Name, ci1.country as [YEAR], ci2.country as COUNTRY 
FROM car 
INNER JOIN car_info AS ci1 ON Car.ID = ci1.car_id AND ci1.field_name = 'year' 
INNER JOIN car_info AS ci2 ON Car.ID = ci2.car_id AND ci2.field_name = 'country'

來源

2013-03-21 11:07:32 GrandMasterFlush

這是最輕，最正確的答案。感謝 – cosset 2013-03-21 11:20:46

WITH car AS (
    SELECT 1 AS id, 'BMW' AS name FROM dual 
    UNION ALL 
    SELECT 2, 'Fiat' FROM dual 
) 
, car_info AS (
    SELECT 1 AS car_id, 'Year' AS field_name, '2000' AS field_val FROM dual 
    UNION ALL 
    SELECT 1, 'Country', 'Germany' FROM dual 
    UNION ALL 
    SELECT 2, 'Year', '1988' FROM dual 
    UNION ALL 
    SELECT 2, 'Country', 'Italy' FROM dual 
) 
    SELECT c.*, car_year.field_val AS yr, car_country.field_val AS country 
    FROM car c 
    JOIN car_info car_year ON c.id = car_year.car_id AND car_year.field_name = 'Year' 
    JOIN car_info car_country ON c.id = car_country.car_id AND car_country.field_name = 'Country' 
;

來源

2013-03-21 11:09:07 Rachcha

' dual'？這是一個oracle查詢。 OP想要'sql server'中的答案 – praveen 2013-03-21 11:14:50

這就是sqlserver – cosset 2013-03-21 11:15:50

然後忘掉'dual'部分。從主「SELECT c。*」開始運行查詢。你會得到你想要的。 – Rachcha 2013-03-21 11:16:12

試試這個：您可以使用PIVOT，然後與Car表

with cte as 
(
Select car_id,[year],[country] 
from 
(Select car_id,field_name,countryName 
    from car_info 
)pv 
pivot 
(
    max(countryName) 
    FOR field_name IN ([year],[country]) 
)pvt 
) 
Select c.name,ct.year,ct.country 
from car c inner join cte ct 
on ct.car_id=c.id

演示中加入SQL Fiddle

來源

2013-03-21 11:09:42 praveen

從多個表中選擇多個列

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