將列轉換爲單獨的表，列名爲值

Question

我正在進行提取，我遇到了一個我無法解決的問題。

我的提取是這樣的：

+--------+-------+----------+----------+-----+------------+ 
| ID  | Info1 | Product1 | Product2 | ... | Product300 | 
+--------+-------+----------+----------+-----+------------+ 
| 1  | Paul | 2  |   |  |   | 
+--------+-------+----------+----------+-----+------------+ 
| 2  | Steve |   | 1  |  |   | 
+--------+-------+----------+----------+-----+------------+ 
| 3  | Mark | 2  |   |  |   | 
+--------+-------+----------+----------+-----+------------+ 
| ... |  |   |   |  |   | 
+--------+-------+----------+----------+-----+------------+ 
| 150000 | Felix | 1  |   |  | 2   | 
+--------+-------+----------+----------+-----+------------+ 

產品顯示爲列。所以它不是很容易使用。

我想我表產品劃分爲外部表所示：

+--------+----------+-------+ 
| ID  | Product | Value | 
+--------+----------+-------+ 
| 1  | Product1 | 2  | 
+--------+----------+-------+ 
| 2  | Product2 | 1  | 
+--------+----------+-------+ 
| ... |   |  | 
+--------+----------+-------+ 
| 150000 | Product1 | 1  | 
+--------+----------+-------+ 

最初，這是提取在Excel中，但我搬到用於此目的的訪問。

我有SQL的基本知識，但還不足以找出解決方案。

Answer 1

您需要UNPIVOT你的表：

https://technet.microsoft.com/en-us/library/ms177410(v=sql.105).aspx

SELECT ID, Product, Value 
FROM 
    (SELECT ID, Product1, Product2, Product3, Product4, Product5 
    FROM products) p 
UNPIVOT 
    (Value FOR Product IN 
     (Product1, Product2, Product3, Product4, Product5) 
)AS unpvt; 

Answer 2

由於jarlh寫道，唯一的SQL解決方案是這樣的：

INSERT INTO TargetTable (ID, Product, Value) 

SELECT ID, 'Product1' AS Product, Product1 AS Value FROM SrcTable WHERE Product1 IS NOT NULL 
UNION ALL 
SELECT ID, 'Product2' AS Product, Product2 AS Value FROM SrcTable WHERE Product2 IS NOT NULL 
UNION ALL 
etc. 

也許它分解成塊，我m不知道300個UNION ALLs在一個查詢中能夠工作多少。