Question

我有一张扁平的，非规范化的表格：

PRODUCT_ID     LOCATION        PARTNUMBER      PRICE   STATUS
1234567890     9999            5555            10.99   A
1234567890     8888            5555            11.99   A
1234567890     7777            5555             9.99   B
9876543210     9999            3333            15.99   A
9876543210     4444            3333            14.99   A
...

我需要查询它以生成一个如下所示的输出文件：

1234567890|9999|5555|10.99|A,8888|5555|11.99|A,7777|5555|9.99|B
9876543210|9999|3333|15.99|A,4444|3333|14.99|A
...

所以基本上是一种数据格式：

我不确定从哪里开始....我应该使用嵌套查询吗？

Answer 1

你需要创建一个游标来遍历你的表。使用变量来控制表的每一行是否引用相同的产品或新产品。

这样的事情：

DECLARE @OLD_PRODUCT_ID int
set @OLD_PRODUCT_ID = -1

DECLARE MyCursor CURSOR FOR 
select PRODUCT_ID, LOCATION, PARTNUMBER, PRICE, STATUS
FROM YourTable

OPEN MyCursor;

FETCH NEXT FROM MyCursor 
INTO @PRODUCT_ID, @LOCATION, @PARTNUMBER, @PRICE, @STATUS --declare these variables

WHILE @@FETCH_STATUS = 0 BEGIN
    if (@PRODUCT_ID = @OLD_PRODUCT_ID) begin
        -- use the same line
    end ele begin
        -- new product = new line
    end

    @OLD_PRODUCT_ID = @PRODUCT_ID
    FETCH NEXT FROM MyCursor 
    INTO @PRODUCT_ID, @LOCATION, @PARTNUMBER, @PRICE, @STATUS

END
CLOSE MyCursor;
DEALLOCATE MyCursor;

Answer 2

还有一些方法可以实现这个w / o循环，但是sql更难。

地点列表是否有限且很小？

如果是这样，你可以这样做：

select a.product_id || 
     coalesce((select '|' || b.location || '|' || b.partnumber  || '|' || 
                             b.price || '|' || trim(b.status)  || ','
               from session.products b 
               where b.location = '9999' and b.product_id = a.product_id), '') || 

     coalesce((select '|' || c.location || '|' || c.partnumber  || '|' || 
                                 c.price || '|' || trim(c.status)  || ','
               from session.products c 
               where c.location = '8888' and c.product_id = a.product_id), '') 
from (select distinct product_id as product_id from session.products) as a

您为每个位置扩展语句。

有一些方法可以在sql中为一组无限制的位置执行此操作，但是读取/写入/调试并不容易，并且+ Diego的光标解决方案可能更合适。

Answer 3

有趣的是，你可以递归地说：

WITH Ordered_Data (product_id, orderIndex, dataString) as (
     SELECT product_id, location, partnumber, price, status, 
         ROW_NUMBER() OVER(PARTITION_BY product_id ORDER BY product_id, location ASC),
            product_id || '|' || location || '|' || partnumber || '|' ||     
            price || '|' || status   
     FROM Product_Location),

     Combined_Data(product_id, orderIndex, dataString) as (
     SELECT a.product_id, a.orderIndex, a.dataString
     FROM Ordered_Data as a
     JOIN (SELECT product_id, MAX(orderIndex) as orderIndex
           FROM Ordered_Data 
           GROUP BY product_id) as b
     ON b.product_id = a.product_id
     AND b.orderIndex = a.orderIndex
     UNION ALL
     SELECT b.product_id, a.orderIndex, b.dataString || ',' || a.dataString
     FROM Ordered_Data as a
     JOIN Combined_Data as b
     ON b.product_id = a.product_id
     AND b.orderIndex - 1 = a.orderIndex)

SELECT dataString
FROM Combined_Data
WHERE orderIndex = 1

产生预期的结果：

9876543210|9999|3333|15.99|A,9876543210|4444|3333|14.99|A                            
1234567890|9999|5555|10.99|A,1234567890|8888|5555|11.99|A,1234567890|7777|5555|9.99|B

我不保证 fast 如何运行 - 特别是，你需要一个索引（product_id，location）（或类似的，并调整声明）。我相信DB2足够聪明，可以向后读取指标，所以方向并不重要。

作为旁注，我真的希望price是numeric或decimal（精确小数），而不是float或{{ 1}}。

SQL - 非规范化数据导出到平面文件混合分隔符

3 个答案: