Question

以下是数据样本

UnitID     ITEM_Num     Price  
13446      71079        45.57  
13447      71079        45.57  
13448      71079        52.50  
13449      71079        45.57  
13450      71079        36.22

实际数据集大约有100个唯一的UnitID和700个唯一的Item_Num值。我正在尝试确定每个Item_Num的最常见价格，然后选择与该标准不同的任何记录超过指定的百分比。

理想情况下，我们会为每件商品设定标准价格值，但我们不会。找到最常见价值的最佳方法是什么。还有一个功能可能能够快速排名物品，其中变化最多的是价格。

这是SQL Server 2012.

Answer 1

您可以使用GROUP BY语句：

SELECT Price, count(*) FROM my_table GROUP BY Price ORDER BY Price ASC

希望这有帮助！

Answer 2

以下查询应该在SQL Server中有效。它应该以比最常见价格低10％或更高的价格回馈每个ITEM_Num。

;WITH cte AS (
  SELECT 
      RANK() OVER (PARTITION BY ITEM_Num ORDER BY COUNT(1) DESC) AS 'Rank'
  , ITEM_Num
  , Price     
  FROM Units
  GROUP BY ITEM_Num, Price 
)
SELECT u1.UnitID
,      u1.ITEM_Num
,      u1.Price
,      u2.Price AS 'most common price'
FROM Units u1
INNER JOIN cte AS u2
ON u2.ITEM_Num = u1.ITEM_Num
AND u2.Rank = 1
WHERE ABS(u1.Price - u2.Price) >=  (u2.Price * 0.1);

编辑：我写的查询不知道你的DBMS，使用SQL Server的排名功能可能更有效。

编辑2：http://sqlfiddle.com/#!6/74940/33

Answer 3

Create table #t(
UnitID int,

Item_Num int,
Price money
)

Insert into #t(Unitid, Item_Num, Price)
values(13446,      71079,        45.57 ),
(13447,      71079,        45.57), 
(13448,      71079,        52.50), 
(13449,      71079,        45.57),
(13450,      71079,        36.22)



;with cte as (
Select 
Unitid, Item_Num, Price, 
Row_Number() over ( partition by item_num order by price) rownum
from #t
) 

Select 
u.UnitID,
u.Item_Num,
u.Price,
U1.price as CommonPrice,
u.RowNum,
U.Price*0.1,
(u.price +(u.price*0.1)) as NewPrice
from cte as U
inner join #t u1 on u.item_num =u1.item_num

where u.rownum =1

SQL标准值和变体

3 个答案: