加載維度表後的邏輯

Question

如何從關係源填充Dim_tbls？

這些例子表給出：

tbl_sales: id_sales, fk_id_customer, fk_id_product, country, timestamp 
tbl_customer: id_customer, name, adress, zip, city 
tbl_product: id_product, price, product 

我的目標是讓這些屬性進入啓動模式。我遇到的問題是加載維度表的邏輯。我的意思是，我會將什麼數據加載到Dim_Product中？所有tbl_product產品？但是，我怎麼知道有多少銷售是用特定的產品完成的？

分析我想這樣做是：

How many people bought product x. 
How many sales are made from city x. 
How many sales were made between Time x and y. 

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示例數據：

tbl_sales: id_sales | fk_id_customer | fk_id_product | country | timestamp 
       1 |  2  |  1  | UK | 19.11.2013 10:23:22 
       2 |  1  |  2  | FR | 20.11.2013 06:04:22 

tbl_customer: id_customer | name | adress | zip | city 
         1 | Frank|Street X| 211 | London 
         2 | Steve|Street Y| 431 | Paris 

tbl_customer: id_product| Price | product 
         1 | 100,00| Hammer 
         2 | 50,00| Saw 

Answer 1

讓我們先從一個非常簡單的星型架構模型;例如，我假定您不必擔心處理維度屬性的更改。

factSales

DateKey 
    CustomerKey 
    ProductKey 
    Counter (=1; this is a factless fact table) 

dimDate

DateKey 
    Date 
    Year 
    Quarter 
    Month 
    ... 

dimCustomer

CustomerKey 
    Name 
    Address 
    Zip 
    City 

dimProduct

ProductKey 
    Name 
    Price (if it changes, you need move it to factSales) 

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有多少人購買了產品x。

SELECT DISTINCT CustomerKey 
FROM factSales 
WHERE ProductKey IN (SELECT ProductKey 
         FROM dimProduct 
         WHERE Name = 'Product X') 

有多少銷售是從X市制造。

SELECT SUM(Counter) 
FROM factSales 
WHERE CustomerKey IN (SELECT CustomerKey 
         FROM dimCustomer 
         WHERE City = 'City X') 

時間X和Y之間了多少銷售取得。

SELECT SUM(Counter) 
FROM factSales 
WHERE DateKey IN (SELECT DateKey 
        FROM dimDate 
        WHERE Date BETWEEN DateX AND DateY)