使用 Access 在 SQL 中逐年并排比较数据

Question

我需要按年份对数据进行并排比较。

我使用的是 Microsoft Access 2013。

我想要得到的是一个table这样的：

╔══════╦══════════╦ ... ╦═══════╦═══════════════╦══════════════╦════════════╗
║ Zone ║ Customer ║ ... ║ Month ║ Previous year ║ Current year ║ Difference ║
╠══════╬══════════╬ ... ╬═══════╬═══════════════╬══════════════╬════════════╣
║ PD   ║ A        ║ ... ║     1 ║ 100€          ║ 150€         ║ +50€       ║
║ PD   ║ B        ║ ... ║     2 ║ 150€          ║ 100€         ║ -50€       ║
║ PD   ║ C        ║ ... ║     1 ║ 200€          ║ 0€           ║ -200€      ║
║ PD   ║ D        ║ ... ║     2 ║ 0€            ║ 100€         ║ +100€      ║
╚══════╩══════════╩ ... ╩═══════╩═══════════════╩══════════════╩════════════╝

("..." stands for other columns)

确定上一年是2014年，今年是2015年，有了这个table我可以看看：

一位 2014 年的客户在 2015 年购买了更多（客户 A）；
一位 2014 年的客户在 2015 年购买了 less（客户 B）；
一位 2014 年的客户 尚未购买 2015 年（客户 C）；
有一个 2015 年的新客户（客户 D）。

当我有一个 "old" (2014) 客户在 2015 年没有购买时 我需要在 Current 中看到价值为“0€”的那一行年列 (2015) 和 2015 年的新客户一样，显然在 2014 年没有购买任何东西。

这些是我的 table：

CUSTOMERS (id, company_name, id_zone, id_customer_category)
CUSTOMER_CATEGORIES (id, description)
订单（id，id_customer，日期，数量，金额（€），id_product_category， id_import)
PRODUCT_CATEGORIES（id、供应商、描述）
ZONES (id, city)
IMPORTS（id、年、月、供应商）

我创建了一个视图（V_YEAR_SALES）：

SELECT Z.ID AS ID_ZONE, Z.CITY, C.COMPANY_NAME AS CUSTOMER, CAT.DESCRIPTION AS CUSTOMER_CATEGORY, P.SUPPLIER, P.DESCRIPTION AS PRODUCT_CATEGORY, I.MONTH, I.YEAR, SUM(O.AMOUNT) AS AMOUNT
FROM ((((ORDERS AS O 
    INNER JOIN CUSTOMERS AS C ON O.ID_CUSTOMER = C.ID) 
    INNER JOIN ZONES AS Z ON Z.ID = C.ID_ZONE) 
    INNER JOIN IMPORTS AS I ON I.ID = O.ID_IMPORT) 
    INNER JOIN CUSTOMER_CATEGORIES AS CAT ON CAT.ID = C.ID_CUSTOMER_CATEGORY)
    INNER JOIN PRODUCT_CATEGORIES AS P ON O.ID_PRODUCT_CATEGORY = P.ID
GROUP BY Z.ID, Z.CITY, C.COMPANY_NAME, CAT.DESCRIPTION, P.SUPPLIER, P.DESCRIPTION, I.MONTH, I.YEAR
ORDER BY Z.CITY, P.SUPPLIER, P.DESCRIPTION, CAT.DESCRIPTION, C.COMPANY_NAME, I.YEAR, I.MONTH;

每次我需要在一年和前一年之间进行比较时，我都会使用这个视图（V_SALES_COMPARISON）通过年份：

SELECT S1.ID_ZONE, S1.CITY, S1.ID_CUSTOMER, S1.CUSTOMER, S1.ID_CUSTOMER_CATEGORY, S1.CUSTOMER_CATEGORY, S1.SUPPLIER, S1.ID_PRODUCT_CATEGORY, S1.PRODUCT_CATEGORY, S1.YEAR, S1.MONTH, S1.AMOUNT AS CURRENT_YEAR, S2.AMOUNT AS PREVIOUS_YEAR, S1.AMOUNT - S2.AMOUNT AS DIFFERENCE
FROM 
    (SELECT * FROM V_YEAR_SALES) AS S1 
    LEFT JOIN 
    (SELECT * FROM V_YEAR_SALES) AS S2 
        ON (S1.ID_ZONE = S2.ID_ZONE) 
        AND (S1.SUPPLIER = S2.SUPPLIER) 
        AND (S1.ID_PRODUCT_CATEGORY = S2.ID_PRODUCT_CATEGORY) 
        AND (S1.ID_CUSTOMER_CATEGORY = S2.ID_CUSTOMER_CATEGORY) 
        AND (S1.ID_CUSTOMER = S2.ID_CUSTOMER) 
        AND (S1.YEAR = S2.YEAR + 1) 
        AND (S1.MONTH = S2.MONTH);

参照上述想要的结果table，使用这个视图我只能获取客户A、B、D的行但是不是 C!

我需要包括 2015 年尚未购买的 2014 年客户！

我正在使用 JOIN，但我不知道这是否是最佳方法。也许我可以使用 PIVOTING，但我不知道是否以及如何使用 Access 实现。

Answer 1

你可以这样走：

SELECT 
    Customer, 
    Sum(IIf(DateDiff("yyyy",[InvoiceDate],Date())=1,[Amount],0)) AS LastYear, 
    Sum(IIf(DateDiff("yyyy",[InvoiceDate],Date())=0,[Amount],0)) AS ThisYear, 
    Sum(IIf(DateDiff("yyyy",[InvoiceDate],Date())=0,[Amount],0)) 
       - Sum(IIf(DateDiff("yyyy",[InvoiceDate],Date())=1,[Amount],0)) AS Diff
FROM 
    Invoices
GROUP BY 
    Customer;

我看到你有一个单独的年份字段，所以试试这个方法：

SELECT 
    Customer, 
    Sum(IIf(Year(Date())-[YearField]=1,[Amount],0)) AS LastYear, 
    Sum(IIf(Year(Date())-[YearField]=0,[Amount],0)) AS ThisYear, 
    Sum(IIf(Year(Date())-[YearField]=0,[Amount],0)) 
       - Sum(IIf(Year(Date())-[YearField]=1,[Amount],0)) AS Diff
FROM 
    Invoices
GROUP BY 
    Customer;

Answer 2

最后我找到了使用 PIVOTING 的解决方案。

V_YEAR_SALES 视图已替换为：

TRANSFORM
IIF(SUM(O.AMOUNT) IS NULL, 0, SUM(O.AMOUNT))
SELECT Z.ID AS ID_ZONE, Z.CITY, C.COMPANY_NAME AS CUSTOMER, CAT.DESCRIPTION AS CUSTOMER_CATEGORY, P.SUPPLIER, P.DESCRIPTION AS PRODUCT_CATEGORY, I.MONTH, I.YEAR
FROM ((((ORDERS AS O 
    INNER JOIN CUSTOMERS AS C ON O.ID_CUSTOMER = C.ID) 
    INNER JOIN ZONES AS Z ON Z.ID = C.ID_ZONE) 
    INNER JOIN IMPORTS AS I ON I.ID = O.ID_IMPORT) 
    INNER JOIN CUSTOMER_CATEGORIES AS CAT ON CAT.ID = C.ID_CUSTOMER_CATEGORY)
    INNER JOIN PRODUCT_CATEGORIES AS P ON O.ID_PRODUCT_CATEGORY = P.ID
WHERE I.YEAR BETWEEN 
    (SELECT MAX(YEAR) FROM IMPORTS) AND (SELECT MAX(YEAR)-3 FROM IMPORTS)
GROUP BY Z.ID, Z.CITY, C.COMPANY_NAME, CAT.DESCRIPTION, P.SUPPLIER, P.DESCRIPTION, I.MONTH, I.YEAR

V_SALES_COMPARISON 视图已删除，因为不再需要。我的查询现在仅适用于 V_YEAR_SALES.

查询新 V_YEAR_SALES 也比 V_SALES_COMPARISON快。

如果需要从Access或不带参数查询视图：

SELECT S.*
FROM V_YEAR_SALES AS S
WHERE S.YEAR IN (2015, 2014) AND S.MONTH BETWEEN 1 AND 12;

相反，如果您需要使用 Jet Driver 从代码中查询视图并且您还想使用参数，则需要这样做：

PARAMETERS P0 TEXT(255), P1 TEXT(255), P2 TEXT(255), P3 TEXT(255);
SELECT S.*
FROM V_YEAR_SALES AS S
WHERE S.YEAR IN (@P0, @P1) AND S.MONTH BETWEEN @P2 AND @P3;

小心包含 PARAMETERS 声明（在 SELECT 语句之前也包含 ;），否则 Jet Driver 会出错:

The Microsoft Jet database engine does not recognize '[P0]' as a valid field name or expression.

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