Question

我有一个使用TOP 1子句（query2）的查询，我想加入另一个使用聚合函数的查询，但我不知道该怎么做。

我想要一个看起来像这样的结果查询：

"select Count(*), Avg(AmtSpent), TOP 1 (Outlet_Code)...."

请劝告。感谢。

查询1：

select Count(*), Avg(AmtSpent) from Transact Where CardNo In
(Select CardNo from Card where MemberID = 'Mem003')

查询2：

select TOP 1 (Outlet_Code) from Transact where CardNo In
(Select CardNo from Card where MemberID = 'Mem003')
group by Outlet_Code
Order by count(Outlet_Code) desc

Answer 1

执行第一个查询并应用另一个查询：

-- Temp tables for demo
CREATE TABLE #Transact (
    ID  INT PRIMARY KEY,
    AmtSpent NUMERIC(18,2),
    CardNo INT,
    Outlet_Code VARCHAR(10)
)

CREATE TABLE #Card (
    CardNo INT PRIMARY KEY,
    MemberID VARCHAR(10)
)

-- Some mock values
INSERT #Card VALUES (1, 'Mem001')
INSERT #Card VALUES (2, 'Mem002')
INSERT #Card VALUES (3, 'Mem003')
INSERT #Card VALUES (4, 'Mem004')
INSERT #Card VALUES (5, 'Mem005')
INSERT #Card VALUES (6, 'Mem006')
INSERT #Card VALUES (7, 'Mem007')
INSERT #Card VALUES (8, 'Mem008')
INSERT #Card VALUES (9, 'Mem009')

INSERT #Transact VALUES (1, 100.0, 1, 'Outlet 1')
INSERT #Transact VALUES (2, 200.0, 1, 'Outlet 2')
INSERT #Transact VALUES (3, 300.0, 2, 'Outlet 3')
INSERT #Transact VALUES (4, 400.0, 2, 'Outlet 4')
INSERT #Transact VALUES (5, 500.0, 3, 'Outlet 5')
INSERT #Transact VALUES (6, 600.0, 8, 'Outlet 6')
INSERT #Transact VALUES (7, 700.0, 9, 'Outlet 7')

DECLARE @MemberID VARCHAR(10)

SET @MemberID = 'Mem002'

-- The query
SELECT
    COUNT(*) AS Count,
    AVG(T.AmtSpent) AS Average,
    _T.Outlet_Code
FROM
    #Transact T

    INNER JOIN #Card C ON
    T.CardNo = C.CardNo

    OUTER APPLY (
        SELECT
            TOP 1 Outlet_Code
        FROM
            #Transact _T

            INNER JOIN #Card C ON
            _T.CardNo = C.CardNo
        WHERE
            C.MemberID = @MemberID
        GROUP BY
            Outlet_Code
    ) AS _T
WHERE
    C.MemberID = @MemberID
GROUP BY
    _T.Outlet_Code

-- Clean up mock stuff
DROP TABLE #Card
DROP TABLE #Transact

Answer 2

这样的东西，只要每个子查询只返回一行，看起来就是这种情况，因为你的一个查询选择了前1，而另一个没有group by子句。这适用于SQL Server 2008。

select TransactCount, TransactAvg, OutletCode
from
(

    select TOP 1 (Outlet_Code) as OutletCode 
    from Transact where CardNo In
    (Select CardNo from Card where MemberID = 'Mem003')
    group by Outlet_Code
    Order by count(Outlet_Code) desc


) rsOutletCode
cross join
(

    select Count(*) as TransactCount, Avg(AmtSpent) as TransactAvg
    from Transact 
    Where CardNo In
    (Select CardNo from Card where MemberID = 'Mem003')

) rsTransact

如何将使用top 1子句的查询加入到使用聚合函数的查询中？

2 个答案: