轉換多個子查詢轉換爲連接（連接表本身）

Table structures 

Table Products : 
============================================= 
ID | Store | Type | Cost | NetCost | 
============================================= 
1 |102 | 0 |14.95 | 29.65 
2 |103 | 1 |13.95 | 32.65 
3 |104 | 2 |12.36 | 42.12 
4 |105 | 3 |10.24 | 23.11 
5 |106 | 4 |19.57 | 27.16 
6 |102 | 0 |57.26 | 26.98 
7 |103 | 3 |43.26 | 26.98 
8 |104 | 4 |10.26 | 26.98 
9 |105 | 1 |9.26 | 26.98 
10 |105 | 5 |11.26 | 46.98 


Same table separated into two tables by Type 
Premium products : Type = (0, 1, 2) 
Basic products : Type = (3, 4, 5) 

Table Products : Products with Type (0,1,2) 
============================================= 
ID | Store | Type | Cost | NetCost | 
============================================= 
1 |102 | 0 |14.95 | 29.65 
2 |103 | 1 |13.95 | 32.65 
3 |104 | 2 |12.36 | 42.12 
6 |102 | 0 |57.26 | 26.98 
9 |105 | 1 |9.26 | 26.98 

Table Products : Products with Type (3,4,5) 
============================================= 
ID | Store | Type | Cost | NetCost | 
============================================= 
4 |105 | 3 |10.24 | 23.11 
5 |106 | 4 |19.57 | 27.16 
7 |103 | 3 |43.26 | 26.98 
8 |104 | 4 |10.26 | 26.98 
10 |105 | 5 |11.26 | 46.98

我要總結數，成本和NetCost基於由商店分組類型的所有產品。結果應如下所示：轉換多個子查詢轉換爲連接（連接表本身）

Table of totals: (B = Basic, P= Premium) 
================================================================= 
Store | B Cnt |B Cost | B NetCost | P Cnt | P Cost | P NetCost | 
================================================================= 
102 
103 
104 
105 
106

我可以通過使用主查詢與下面所示的子查詢實現上述，是否有更有效的連接（接合表本身等）我可以做那會達到上面的表格（總數）？

子查詢，我會放在一個主查詢：

SELECT 
    count(*) 
FROM 
    Products prod_prem 
WHERE 
    (prod_prem.Type = 0 OR prod_prem.Type = 1 OR prod_prem.Type = 2) 

SELECT 
    SUM(Cost), 
FROM 
    Products prod_prem 
WHERE 
    (prod_prem.Type = 0 OR prod_prem.Type = 1 OR prod_prem.Type = 2) 

SELECT 
    SUM(NetCost) 
FROM 
    Products prod_prem 
WHERE 
    (prod_prem.Type = 0 OR prod_prem.Type = 1 OR prod_prem.Type = 2) 


SELECT 
    count(*) 
FROM 
    Products prod_basic 
WHERE 
    (prod_prem.Type = 3 OR prod_prem.Type = 4 OR prod_prem.Type = 5) 


SELECT 
    SUM(Cost), 
FROM 
    Products prod_basic 
WHERE 
    (prod_prem.Type = 3 OR prod_prem.Type = 4 OR prod_prem.Type = 5) 


SELECT 
    SUM(NetCost) 
FROM 
    Products prod_basic 
WHERE 
    (prod_prem.Type = 3 OR prod_prem.Type = 4 OR prod_prem.Type = 5)

來源

2017-01-13 Fabii

您可以在單一的查詢使用Conditional Aggregation

SELECT Store, 
     [B Cnt] = Count(CASE WHEN Type IN (3, 4, 5) THEN 1 END), 
     [B Cost] = Sum(CASE WHEN Type IN (3, 4, 5) THEN Cost ELSE 0 END), 
     [B NetCost] = Sum(CASE WHEN Type IN (3, 4, 5) THEN NetCost ELSE 0 END), 
     [P Cnt] = Count(CASE WHEN Type IN (0, 1, 2) THEN 1 END), 
     [P Cost] = Sum(CASE WHEN Type IN (0, 1, 2) THEN Cost ELSE 0 END), 
     [P NetCost] = Sum(CASE WHEN Type IN (0, 1, 2) THEN NetCost ELSE 0 END) 
FROM Products 
GROUP BY Store

來源

2017-01-13 16:37:29

這看起來更清潔，更容易理解，我會在今天晚些時候嘗試，如果能解決問題，請接受您的答案。格拉西亞斯。 – Fabii

你應該有帶IsPremium位列ProductType表做到這一點。這樣，當類型6，7，8出現時，您不必對代碼進行可怕的錯誤維護 - 您只需在類型表中插入新行。

來源

2017-01-13 16:41:12

我不保留表格，所以我必須和他們一起工作。 – Fabii

Gotcha。如果這存在於存儲過程中，則可以在過程中將其創建爲臨時表，因此「高級」僅在proc中的一個位置定義，而不是多個。可能比它的價值更麻煩，只是一個建議 –

謝謝，我會牢記這一點。 – Fabii

轉換多個子查詢轉換爲連接（連接表本身）

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