[英]SQL - Combining two queries
我有两个我想要结合的查询。
查询1 - 这告诉我库存中的所有车辆。 含义不在所有权表中:
SELECT VEHICLE.*
FROM VEHICLE
WHERE NOT EXISTS
(SELECT NULL FROM OWNERSHIP WHERE VEHICLE.VEH_ID= OWNERSHIP.VEH_ID);
查询2 - 这个告诉我哪个车是每个品牌的最高价格。
SELECT B.BRAND_ID, B.BRAND_NAME, M.MODEL_NAME, C.CLASS_NAME, V.VEH_ID, V.VEH_YEAR, V.VEH_PRICE
FROM (((VEHICLE AS V INNER JOIN CLASS AS C ON V.CLASS_ID = C.CLASS_ID)
INNER JOIN MODEL AS M ON M.MODEL_ID = V.MODEL_ID)
INNER JOIN BRAND AS B ON B.BRAND_ID = M.BRAND_ID)
INNER JOIN (SELECT M.BRAND_ID, MAX(V.VEH_PRICE) AS VEH_PRICE FROM VEHICLE AS V
INNER JOIN MODEL AS M ON M.MODEL_ID = V.MODEL_ID GROUP BY M.BRAND_ID)
AS derived ON (v.VEH_PRICE = derived.VEH_PRICE) AND (b.BRAND_ID = derived.BRAND_ID)
ORDER BY 7 DESC;
我意识到,确定哪些车辆是最昂贵的车辆,如果它们已经由客户拥有则无关紧要。 由于第一个查询告诉我们哪些可用,我将如何将这两个结合起来?
我无法测试您的查询,但认为这是您正在寻找的:
SELECT
B.BRAND_ID,
B.BRAND_NAME,
M.MODEL_NAME,
C.CLASS_NAME,
V.VEH_ID,
V.VEH_YEAR,
V.VEH_PRICE
FROM
(((VEHICLE AS V INNER JOIN CLASS AS C ON V.CLASS_ID = C.CLASS_ID)
INNER JOIN MODEL AS M ON M.MODEL_ID = V.MODEL_ID)
INNER JOIN BRAND AS B ON B.BRAND_ID = M.BRAND_ID)
INNER JOIN (SELECT M.BRAND_ID, MAX(V.VEH_PRICE) AS VEH_PRICE
FROM VEHICLE AS V
INNER JOIN MODEL AS M
ON M.MODEL_ID = V.MODEL_ID
WHERE
NOT EXISTS
(SELECT NULL FROM OWNERSHIP
WHERE V.VEH_ID=OWNERSHIP.VEH_ID)
GROUP BY M.BRAND_ID) AS derived
ON (v.VEH_PRICE = derived.VEH_PRICE)
AND (b.BRAND_ID = derived.BRAND_ID)
WHERE
NOT EXISTS
(SELECT NULL FROM OWNERSHIP
WHERE V.VEH_ID=OWNERSHIP.VEH_ID)
ORDER BY 7 DESC;
您必须排除子查询中已经拥有的汽车,您可以在其中计算每个品牌的最高价格,也可以在外部查询中排除与拥有所有者的汽车最大价格相同的自有汽车。
我还建议在子查询和外部查询中再添加一个带有OWNERSHIP的LEFT JOIN,而不是使用NOT EXISTS子句,并且只采用OWNERSHIP.VEH_ID为空的行。
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