SQL查詢聯接/聯合兩個表

Question

我正在尋找一些建議，以建立一個查詢來聯接表A和表B，以將輸出作為表C。看起來我需要能夠將兩個表結合起來並建立一個交叉表查詢。 下面顯示的數據僅是示例，因為兩個表中的日期每月都會更改。 注意：兩個表格中的日期不會重疊。 例如，在表B下面將永遠不會有FutureDate作為六月或七月。 反之亦然

Table A
Product Location HistoryDate HistorySales ... more columns
 A         X         June      100
 A         X         July      200

Table B
Product Location FutureDate FutureSales   ... more columns
 A         X         August    150
 A         X         Sept      50

Table C
Product Location June July August September ... other columns from A & B
 A         X     100  200    150    50

謝謝你的幫助。

Answer 1

這已在SQL Server 2008 R2中進行了測試。 我相信這里的所有內容都將在2005年正常運行。 據我所知，2005年推出了PIVOT和OVER等產品。 如果您發現任何問題，請告訴我。

DECLARE @Products TABLE
(
    ID INT IDENTITY(1, 1)
    , Name VARCHAR(30)
);

INSERT INTO @Products
VALUES ('Dummies Guide to Querying'), ('SQL Design Patterns');

DECLARE @OldProducts TABLE
(
    ID INT IDENTITY(1, 1)
    , ProductID INT
    , Location CHAR(2)
    , HistoryDate DATE
    , Sales INT
);

INSERT INTO @OldProducts
VALUES (1, 'CO', '20100601', 100)
    , (1, 'CO', '20100701', 200)
    , (1, 'CA', '20100526', 150)
    , (2, 'CA', '20100601', 175);

DECLARE @NewProducts TABLE
(
    ID INT IDENTITY(1, 1)
    , ProductID INT
    , Location CHAR(2)
    , FutureDate DATE
    , PredictedSales INT
);

INSERT INTO @NewProducts
VALUES (1, 'CO', '20110401', 200)
    , (1, 'CO', '20110601', 250)
    , (1, 'CA', '20110401', 150)
    , (2, 'CA', '20110301', 180)
    , (3, 'WA', '20110301', 100);

WITH AllProduts AS
(
    SELECT
        Products.Name
        , OldProducts.Location
        , DATENAME(MONTH, OldProducts.HistoryDate) AS MonthValue
        , OldProducts.Sales
    FROM @OldProducts AS OldProducts
    INNER JOIN @Products AS Products
        ON Products.ID = OldProducts.ProductID

    UNION ALL

    SELECT
        Products.Name
        , NewProducts.Location
        , DATENAME(MONTH, NewProducts.FutureDate) AS MonthValue
        , NewProducts.PredictedSales AS Sales
    FROM @NewProducts AS NewProducts
    INNER JOIN @Products AS Products
        ON Products.ID = NewProducts.ProductID
)
SELECT
    Name
    , Location
    , [January]
    , [Febuary]
    , [March]
    , [April]
    , [May]
    , [June]
    , [July]
    , [August]
    , [September]
    , [October]
    , [November]
    , [December]
FROM AllProduts
PIVOT
(
    SUM(Sales)
    FOR MonthValue
    IN
    (
        [January]
        , [Febuary]
        , [March]
        , [April]
        , [May]
        , [June]
        , [July]
        , [August]
        , [September]
        , [October]
        , [November]
        , [December]
    )
) PivotedTable
ORDER BY Name, Location;